Encyclopedia of Global Resources part 48 pptx

418 • Feldspars Global Resources
Million Metric Tons
Source: Mineral Commodity Summaries, 2009Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.
Argentina
Brazil
China
Colombia
Czech Republic
Egypt
France
Germany
India
Iran
Italy
Japan
Malaysia
Mexico
Poland
Portugal
South Korea
Spain
Thailand
Turkey
United States
Venezuela
Other countries
290,000
130,000
2,000,000
100,000
490,000

350,000
170,000
160,000
260,000
4,200,000
250,000
350,000
130,000
400,000
600,000
3,800,000
200,000
650,000
700,000
440,000
800,000
600,000
1,200,000
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Feldspar: World Mine Production, 2008
icut, togrindfeldspar forthe newly developedpottery
industry in the United States.
The largest production of feldspar in the United
States is in North Carolina, followed by Virginia, Cali-
fornia, Oklahoma, Georgia, Idaho, and South Dakota.
Crude feldspar is also produced by at least thirty-eight
other countries. China, Turkey, Italy, and Thailand
jointly produce approximately 60 percent of the
world’s total feldspar. U.S. production of crude feld-
spar is about 3 percent of the world total.

Obtaining Feldspar
The method used to obtain feldspar depends on
the type of deposit to be mined. Most feldspar can
be quarried by open-pit mining. Some feldspars are
mined by boring down through distinct zones within
pegmatite dikes, but many deposits require the use of
explosives and drills. Dragline excavators are used to
mine feldspathic sands. High-grade feldspar can be
dry-processed. It is sent through jaw crushers, rolls,
and oiledpebble mills,and is finally subjected tohigh-
intensity magnetic or electrostatic treatments that re-
duce the iron content to acceptable levels.
Feldspathic sands are crushed and rolled, then
processed by a three-step froth flotation sequence
that removes mica, extracts the iron-bearing miner
-
als, and finally separates the quartz residuals. Some-
times the last flotation procedure is omitted so that
a feldspar-quartz mixture can be sold to the glass-
making industry. The feldspar is ground to about
twenty mesh for glassmaking and to two hundred
mesh or finer for ceramic and filler applications.
Uses of Feldspar
Feldspar is used in the manufacturing of soaps, glass,
enamels, and pottery. As a scouring soap, its interme-
diate hardness, angular fracture, and two directions
of cleavage cause it to form sharp-edged, gritty parti-
cles that are hard enough to abrade but soft enough
not to cause damage to surfaces. In glassmaking, feld-
spar brings alumina, together with alkalies, into the

melt. This enhances the workability of the glass for
shaping and gives it better chemical stability.
Feldspar is used primarily as a flux in ceramics mix-
tures to make vitreous china and porcelain enamels.
The feldspar is ground to a very fine state and mixed
with kaolin or clay and quartz. The feldspar fuses at a
temperature below most of the other components
and acts as a vitreous binder, cementing the material
together. Fused feldspar is also used as the major part
of the glaze on porcelain ware.
Dion C. Stewart
Further Reading
Chatterjee, Kaulir Kisor. “Feldspar.” In Uses of Indus-
trial Minerals, Rocks, and Freshwater. New York: Nova
Science, 2009.
Deer, W. A., R. A. Howie, and J. Zussman. Framework
Silcates: Feldspars. Vol 4A in Rock-Forming Minerals.
2d ed. London: Geological Society, 2001.
Klein, Cornelis, and Barbara Dutrow. The Twenty-third
Edition of the Manual of Mineral Science. 23d ed.
Hoboken, N.J.: J. Wiley, 2008.
Kogel, Jessica Elzea, et al., eds. “Feldspars.” In Indus-
trial Minerals and Rocks: Commodities, Markets, and
Uses. 7th ed. Littleton, Colo.: Society for Mining,
Metallurgy, and Exploration, 2006.
Ribbe, R. H., ed. Feldspar Mineralogy. 2d ed. Washing-
ton, D.C.:Mineralogical Societyof America,1983.
Smith, Joseph V., and William L. Brown. Feldspar Min-
erals. 2d rev. and extended ed. New York: Springer,
1988.

Wenk, Hans-Rudolf, and Andrei Bulakh. Minerals:
Their Constitution and Origin. New York: Cambridge
University Press, 2004.
Global Resources Feldspars • 419
Source: Mineral
Commodity Summaries, 2009
Data from the U.S. Geological Survey,
.U.S.GovernmentPrinting
Office, 2009.
Glass
65%
Pottery
and other
35%
U.S. End Uses of Feldspar
Web Sites
U.S. Geological Survey
Feldspar
/>commodity/gemstones/sp14-95/feldspar.html
U.S. Geological Survey
Feldspar: Statistics and Information
/>commodity/feldspar
See also: Abrasives; Ceramics; China; France; Igne-
ous processes, rocks, and mineral deposits; Italy; Mex-
ico; Pegmatites; Plutonic rocks and mineral deposits;
Spain; Thailand; Turkey; United States.
Fermi, Enrico
Category: People
Born: September 29, 1901; Rome, Italy
Died: November 28, 1954; Chicago, Illinois

Fermi was an Italian physicist knownfor his workon
the first nuclear reactor and his theory of beta decay.
He contributedto quantum theory, statistical mechan-
ics, and nuclear and particle physics. He conducted
investigations on the atom’s nucleus and experi-
mented with uranium, which led to his observation
of nuclear fission. His discovery of a methodology to
release nuclear energy earned him the Nobel Prize in
Physics in 1938.
Biographical Background
Enrico Fermi was born in Rome, Italy, the son of a
railroad official and a schoolteacher. He excelled
in school, sharing his interests with his older
brother, Giulio, who died in 1915 after minor
throat surgery. After high school, Fermi studied
at the University of Pisa from 1918 to 1922, com-
pleting his undergraduate degree and Ph.D. in
physics. Fermi solved the Fourier analysis for his
college entrance exam and published his first sci-
entific work on electrical charges in transient
conditions in 1921.
Fermi received a fellowship to work at the Uni-
versity of Göttingen in Germany in 1924. He
taught math at the University of Rome and the
University of Florence, where he researched what
would later be called the Fermi-Dirac statistics. Fermi
studied at Leyden in the Netherlands and married
Laura Capon in 1928. Their daughter, Nella Fermi
Weiner (1931-1995), and son, Giulio (1936-1997),
both obtainedPh.D.’s.Fermi wasone of the only phys-

icists of the twentieth century toexcel in both theoret-
ical and applied nuclear physics. He died from stom-
ach cancer, resulting from radiation exposure, on
November 28, 1954.
After his death, his lecture notes were transcribed
into books, andschools and many awards were named
in his honor. Three nuclear reactor installations were
named after him, as was “fermium,” the one hun-
dredth element on the periodic table.
Impact on Resource Use
Fermi’s research at the University of Rome led to the
discovery of uranium fission in 1934. In 1939, on the
Columbia University campus, the first splitting of
the uranium atom took place. Fermi’s focus was on
420 • Fermi, Enrico Global Resources
Enrico Fermi’s work with radioactiveisotopes led to the development of the
atomic bomb. (NARA)
the isotope separation phase of the atomic energy
project. In 1942, he led a famous team of scientists
in lighting the first atomic fire on earth at the Univer-
sity of Chicago. His studies led to the construction of
the first nuclear pile, called Chicago Pile-1, whereby
he assessedthe properties offission, thekey toextract-
ing energy from nuclear reactions.
Another example of his impact was noted on July
16, 1945, when Fermi supervised the design and as-
sembly of the atomic bomb. Fermi dropped small
pieces of paper as the wave of the blast reached him
and then measured the distance those pieces were
blown. This allowed him to estimate the bomb’s en-

ergy yield. The calculations became known as the
“Fermi method.” His discovery of how to release nu-
clear energy encouraged the development of many
peaceful uses for nuclear energy.
Fermi discovered induced radioactivity (radioac-
tive elements produced by the irradiation of neu-
trons) and nonexplosive uranium, which is trans-
muted into plutonium (a vital element in the atomic
and hydrogen bombs and the first atomic subma-
rine). His research led to the creation of more than
forty artificial radioactive isotopes, and his theory of
neutron decay became the model for future theories
of particle interaction.
Gina M. Robertiello
See also: Hydrogen; Nobel, Alfred; Nuclear energy;
Nuclear Energy Institute; Uranium.
Ferroalloys
Category: Mineral and other nonliving resources
Where Found
Ferroalloy production occurs in many countries
around the world, but the primary ferroalloy-produc-
ing countries are China, South Africa, Ukraine, Russia,
and Kazakhstan. These five countries produce more
than 74 percent of the world’s ferroalloy supply. How-
ever, because the various ferroalloys contain a num-
ber ofdifferentelements, manyparts ofthe worldsup-
ply minerals important in ferroalloy production.
Primary Uses
Ferroalloys are used extensively in the iron and steel
industry. The type of alloy produced depends upon

the properties of the element that is added to the
iron. Stainless steel, high-strength steels, tool steels,
and cast irons are the major ferroalloy products. Some
ferroalloys are also used to produce metal coatings,
catalysts, electrodes, lighting filaments, aerospace and
marine products, medical implants, and household
batteries.
Technical Definition
Ferroalloys constitute a wide variety of alloyed metals
that combine alarge percentage of iron with a smaller
percentage of one or more elements. Combining
other elements with iron imparts superior strength
to thesealloys, and thisincreased strengthenables the
metals to be used in many important products within
the metallurgical industry. Ferroalloys have lower
melting points than do the pure elements that form
them; therefore, they are incorporated more easily
into molten metal. Manganese, chromium, magne-
sium, molybdenum, nickel, titanium, vanadium, sili-
con, cobalt, copper, boron, phosphorus, niobium,
tungsten, aluminum, and zirconium are the primary
elements mixed in varying proportions with iron to
produce ferroalloys. Ferroalloys are produced pri-
marily in electric arc furnaces; the nonferrous metal
combines with the iron at high temperatures to pro-
duce the various types of steel.
Description, Distribution, and Forms
Much of the stainless-steel production of Europe, Asia,
and North and South America is possible because of
ferrochromium.In 2007,approximately 29metric tons

of stainless steel were produced throughout the world.
Most chromite ore miningtakes placein China, India,
South Africa, Russia, Turkey, and Kazakhstan. The ma-
jority of chromiteore is smelted in electric arc furnaces
to produce ferrochromium,which is thenexported to
the countries that manufacture stainless steel.
Ferromanganeseand silicomanganese are primary
ingredients in steelmaking. Most of the U.S. supply of
these alloys is imported from South Africa, although
China, Brazil, India, and Ukraine are also important
producers. The United States also produces some
ferromanganese at a plant near Marietta, Ohio. Be-
sides being a key component in steel manufacturing,
manganese is used in the production of household
batteries. Silicomanganese production at plants in
New Haven, West Virginia, the United Kingdom, and
Ukraine has been vital to steelmaking for a number of
years.
Global Resources Ferroalloys • 421
Ferrosilicon is a deoxidizing agent in cast iron and
steel production. China, Brazil, and Russia are the
main producers offerrosilicon, withChina producing
more than four times as much as the other two coun-
tries.
More than 99 percent of ferronickel use within the
United States is for stainless steel and heat-resistant
steel. Stainless-steel cooking pots, pans, and kitchen
sinks are products of the ferronickel industry. The
United States does not produce any primary nickel
but instead produces a remelt alloy with small per-

centages ofchromium and nickelfrom recycledmate-
rials. Japan, New Caledonia, Colombia, Greece,
Ukraine, Indonesia, the Dominican Republic, and
Venezuela lead the world in ferronickel production.
Another major ferroalloy is ferromolybdenum, a
component of stainless steels, tool steels, and cast
iron. About 80 percent of world production of ferro-
molybdenum takes place in Chile, China, and the
United States, while the remainder occurs in Canada,
Mexico, and Peru.
Ferrotitanium plays a large role in the steel indus-
try as a deoxidizing and stabilizing agent as well as an
alloy that assists in controlling the grain size of steel.
Titanium is not naturally found in metallic form but
instead is mined from titanates, oxides, and silico-
titanites. Ferrotitanium is then produced by an in-
duction melting process. Steels with a high titanium
content include stainless, high-strength, and intersti-
tial-free (space-free) forms. Other important ferroti-
tanium uses include catalysts, pigments, floor cover-
ings, roofing material, aerospace products, medical
implants, armor, and marine industrial goods. Major
producers of ferrotitanium include China, India, Ja-
pan, Russia, the United Kingdom, and the United
States.
Ferrovanadium, used in the manufacture of cata-
lysts and chemicals, is produced in the United States
mostly from petroleum ash and residues as well as
from tar sands. China and South Africa contribute 71
percent of the world’s supply of ferrovanadium, while

Russia makes up most of the remaining supply.
History
Steel has been produced by a number of methods
since before the fifteenth century, but only since
the seventeenth century has it been produced effi-
ciently. The Bessemer process, invented in the mid-
1800’s by Sir Henry Bessemer, enabled steel to be
mass-produced in a cost-effective manner. Improve
-
ments on theBessemer process included the Thomas-
Gilchrist process and the Siemens-Martin process of
open-hearth steel manufacture. Basic oxygen steel-
making, also known as the Linz-Donawitz process, was
developed in the 1950’s, and although the Bessemer
process and other processes continued to be used for
a few more years, basic oxygen steelmaking soon
became the process of choice for modern steel manu-
facture.
Creating Ferroalloys
Ferroalloys have been used in the steel manufactur-
ing industry primarily since the 1960’s. In the twenti-
eth century, metallurgists discovered that adding vary-
ing amounts of manganese, silicon, or aluminum to
the molten steel pulled oxygen away from the melted
material, thus allowing for sound castings without
bubbles or blowholes. The other ferroalloys—those
containing chromium, tungsten, molybdenum, vana-
dium, titanium, and boron—provide a method for
making specialty steels other than ordinary carbon
steel. By adding small amounts of the other metals,

high-strength, heat-resistant steels, such as stainless
steel, can be produced.
The amount of steel that a country produces is
often considered to be an important indicator of eco-
nomic progress. Therefore, the production of ferro-
alloys within the iron and steel manufacturing indus-
try is also a key factor of the economy of the countries
in which it takes place. In the twenty-first century, the
economic booms in China and India brought about a
large increase in demand for steel products and a cor-
responding needfor a large number of workers inthis
industry. The top producers of steel in the world are,
in order of metric-ton production per year, China, Ja-
pan, Russia, and the United States. Each of these
countries has many thousands of workers in its steel
industry and in the mining industries, which supply
the raw materials for iron and steel production.
Uses of Ferroalloys
The primary use of ferroalloys is in the manufactur-
ing of iron and steel. Combining various metallic ele-
ments with ironresults in a strong, stableproduct vital
to many industries. Stainless and heat-resisting steels
are produced from ferrochromium, ferrotitanium,
and ferronickel. Ordinary carbon steel rusts, but
stainless steel resists corrosion because of the chro
-
mium oxide film it contains. In general, at least 11
percent chromium must be added to the steel in or
-
422 • Ferroalloys Global Resources

der to produce the stainless quality. Up to 26 percent
chromium must be added if the stainless steel is to be
exposed to harsh environmental conditions. Al-
though stainless steel has a huge number of applica-
tions in modern society, it is mostly used for cutlery,
appliances, surgical instruments, cooking equip-
ment, and aerospace parts. Because stainless steel is
also resistant to bacterial growth, it is important in the
cooking and medical industries. Stainless steel is also
used in jewelry and firearm production.
Ferrochromium is used in the chemical industry as
a surface treatment coating for metals. Besides the
primary uses of ferroalloys in steelmaking, these sub-
stances are also used to produce catalysts in catalytic
converters, pigments in paint, grinding and cutting
tools, lighting filaments, and electrodes. Ferrosilicon
is used by the military to produce hydrogen for bal-
loons in a process that combines sodium hydroxide,
ferrosilicon, and water.
Lenela Glass-Godwin
Further Reading
Corathers, Lisa A. “Manganese.” USGS Minerals Year-
book (2007).
Dunkley, J. J., and D. Norval. “Atomisation of Ferro-
alloys.” In Industrial Minerals and Rocks, edited by
Jessica Elzea Kogel. 6thed. Littleton, Colo.: Society
of Mining, Metallurgy, and Exploration, 2004.
Jones, Andrew. “The Market and Cost Environments
for Bulk Ferroalloys.” In International Conference on
Innovations in theFerroalloy Industry. New Delhi:The

Indian Ferro Alloy Producers’ Association, 2004.
Papp, J.F. “Chromite.” InIndustrial Minerals and Rocks,
edited by Jessica Elzea Kogel. 6th ed. Littleton,
Colo.: Society of Mining, Metallurgy, and Explora-
tion, 2004.
Web Site
U.S. Geological Survey
Minerals Information: Ferroalloys Statistics and
Information
/>commodity/ferroalloys/
See also: Aluminum; Bessemer process; Boron;
Chromium; Cobalt; Copper; Magnesium; Manganese;
Molybdenum; Nickel; Niobium; Siemens, William;
Silicon; Steel; Steel industry; Titanium; Tungsten; Va
-
nadium; Zirconium.
Fertilizers
Categories: Plant and animal resources; products
from resources
Fertilizers, those materials that are used to modify the
chemical composition of the soil in order to enhance
plant growth, represent an important use of natural
resources because agricultural systems are dependent
upon the ability to retain soil fertility. Among the essen-
tial nutrients provided in fertilizers are calcium, mag-
nesium, sulfur, nitrogen, potassium, and phosphorus.
Background
It has been said that civilization owes its existence to
the 15-centimeter layer of soil covering the Earth’s
landmasses. This layer of topsoil represents the root

zone for the majority of the world’s food and fiber
crops. Soil is a dynamic, chemically reactive medium,
and agricultural soils must provide structural support
for plants, contain a sufficient supply of plant nutri-
ents, and exhibit an adequate capacity to hold and ex-
change minerals. As plants grow and develop, they re-
move the essential mineral nutrients from the soil.
Since normal crop production usually requires the re-
moval of plants or plant parts, nutrients are continu-
ously being removed from the soil. Therefore, the
long-term agricultural utilization of any soil requires
periodic fertilization to replace these lost nutrients.
Fertilizers are associated with every aspect of this nu-
trient replacement process. The application of fertil-
izer is based on a knowledge of plant growth and de-
velopment, soilchemistry, and plant-soil interactions.
Soil Nutrients
Plants require an adequate supply of both macro-
nutrients (calcium, magnesium, sulfur, nitrogen, po-
tassium, and phosphorus) and micronutrients (iron,
copper, zinc, boron, manganese, chloride, and mo-
lybdenum) from the soil. If any one of these nutrients
is notpresent insufficient amounts, plant growthand,
ultimately, yieldswill be reduced. Becausemicronutri-
ents are required in small quantities and deficiencies
in these minerals occur infrequently, the majority of
agricultural fertilizers contain only macronutrients.
Although magnesium and calcium are utilized in
large quantities, most agricultural soils contain an
abundance ofthese twoelements, eitherderived from

parent material or added as lime. Most soils also con
-
Global Resources Fertilizers • 423
tain sufficient amounts of sulfur from the weathering
of sulfur-containing minerals, the presence of sulfur
in other fertilizers, and atmospheric pollutants.
The remaining three macronutrients (nitrogen,
potassium, and phosphorus) are readily depleted and
are referred toas fertilizer elements. Hence, theseele-
ments must be added to most soils on a regular basis.
Fertilizers containingtwo ormore nutrientsare called
mixed fertilizers. A fertilizer labeled 10-10-10, for
example, means that the product contains 10 percent
nitrogen, 10 percent phosphorus, and 10 percent po-
tassium. Since these elements can be supplied in a
number of different forms, some of which may not be
immediately useful to plants, most states require that
the label reflect the percentage of nutrients available
for plantutilization. Fertilizers are produced ina wide
variety of single and mixed formulations, and the per-
centage of available nutrients generally ranges from a
low of 5percent to ahigh of 33 percent. Mixedfertiliz-
ers may also contain varying amounts of different
micronutrients.
Fertilizer Production
Nitrogen fertilizers can be classified as either chemi-
cal or natural organic. Naturalorganic sources are de-
rived from plant and animal residues and include
such materials as animal manures, cottonseed meal,
and soybean meal. Since natural organic fertilizers

contain relatively small amounts of nitrogen, com-
mercial operations rely on chemical fertilizers de-
rived fromsources otherthan plantsand animals.The
major chemical sources of nitrogen include both am-
monium compounds and nitrates. The chemical fixa-
tion of atmospheric nitrogen by the Claude-Haber
ammonification process is the cornerstone of the
modern nitrogen fertilizer manufacturing process.
Once the ammonia is produced, it can be applied di-
rectly to the soil as anhydrous ammonia, or it can be
mixed with water and supplied as a solution of aque-
ous ammonia and used in chemical reactions to pro-
duce other ammonium fertilizers or urea, or con-
verted to nitrates that can be used to make nitrate
fertilizers.
Some organic fertilizers contain small amounts
of phosphorus, and organically derived phosphates
from guano or acid-treated bonemeal were used in the
past. However, the supply of these materials is scarce.
Almost all commercially produced agricultural phos
-
phates are applied as either phosphoric acid or super
-
phosphate derived from rock phosphate. The major
phosphate component in commercially important
deposits of rock phosphate is apatite. The apatite
is mined, processed to separate the phosphorus-
containing fraction from inert materials, and then
treated with sulfuric acid to break the apatite bond.
The superphosphate precipitates out of the solution

and sets up as a hard block, which can be mechani-
cally granulated to produce a fertilizer containing cal-
cium, sulfur, and phosphorus. Potassium fertilizers,
commonly called “potash,” are also obtained from
mineral depositsbelow theEarth’s surface. Themajor
commercially availablepotassium fertilizers are potas-
sium chloride extracted from sylvanite ore, potassium
sulfate produced by various methods (including ex-
traction from langbeinite or burkeite ores or chemi-
cal reactionswith potassium chloride),and potassium
nitrate, which can be manufactured by several differ-
ent chemical processes. Although limited, there are
sources of organic potassium fertilizers such as to-
bacco stalks and dried kelp.
While the individual nitrogen, phosphorus, and
potassium fertilizers can be applied directly to the
soil, they are also commonly used to manufacture
mixed fertilizers. From two to ten different materials
with widely different properties are mixed togetherin
the manufacturing process. The three most common
processes utilized in mixed fertilizer production are
the ammonification of phosphorus materials and the
subsequent addition of other materials, bulk blend-
ing of solid ingredients, and liquid mixing. Fillers and
make-weight materials are often added to make up
the difference between the weight of fertilizer materi-
als required to furnish the stated amount of nutrient
and the desired bulk of mixed products. Mixed fertil-
izers have the obvious advantage of supplying all the
required nutrients in one application.

Benefits and Costs
For every crop there is a point at which the yield may
continue to increase with application of additional
nutrients, but the increase will not offset the addi-
tional cost of the fertilizer. Therefore, considerable
care should be exercised when applying fertilizer.The
economically feasible practice, therefore, is to apply
the appropriate amount of fertilizer to produce maxi-
mum profit rather than maximum yield. Moreover,
since excessive fertilization can result in adverse soil
reactions that damage plant roots or produce unde
-
sired growth patterns, overfertilization can actually
decrease yields. If supplied in excessive amounts, some
424 • Fertilizers Global Resources
of the micronutrients are toxic to plants and will dra
-
matically reduce plant growth. Fertilizer manufactur-
ers must ensure that their products contain the speci-
fied amounts of nutrients indicated on their labels
and that there are no contaminants that could ad-
versely affect plant yield directly or indirectly through
undesirable soil reactions.
The environment can also be adversely affect by
overfertilization. Excess nutrients can be leached
through the soil into underground water supplies
and/or removed from the soil in the runoff water that
eventually empties into streams and lakes. High levels
of plant nutrients in streams and lakes (eutrophica-
tion) can result in abnormal algal growth, which can

cause serious pollutionproblems. Water thatcontains
excessive amounts of plant nutrients can also pose
health problems if it is consumed by humans or live-
stock.
Importance to Food Production
Without a doubt, the modern use of fertilizer has
dramatically increased crop yields. If food and fiber
production is to keep pace with the world’s growing
population, increasedreliance on fertilizers willbe re-
quired inthe future. With ever-increasing attention to
the environment, future research will primarily be
aimed atfinding fertilizermaterials thatwill remainin
the field to which they are applied and at improving
application and cultivation techniques to contain ma-
terials withinthe designatedapplication area.The use
of technology developed from discoveries in the field
of molecular biology to develop more efficient plants
holds considerable promise for the future.
D. R. Gossett
Further Reading
Altieri, MiguelA. Agroecology:The ScientificBasis ofAlter-
native Agriculture. Boulder, Colo.: Westview Press,
1987.
Black, C. A. Soil-Plant Relationships. 2d ed. Malabar,
Fla.: R. E. Krieger, 1984.
Brady, Nyle C., and Ray R. Weil. The Nature and Prop-
erties of Soils. 14th ed. Upper Saddle River, N.J.:
Prentice Hall, 2008.
Elsworth, Langdon R., and Walter O. Paley, eds. Fertil-
izers: Properties, Applications, and Effects. New York:

Nova Science, 2008.
Engelstad, Orvis P. Fertilizer Technology and Use.3ded.
Madison, Wis.: Soil Science Society of America,
1986.
Follett, RoyH., Larry S.Murphy, andRoy L.Donahue.
Fertilizers and Soil Amendments. Englewood Cliffs,
N.J.: Prentice-Hall, 1981.
Hall, William L., Jr., and Wayne P. Robarge, eds. Envi-
ronmental Impact of Fertilizer on Soil and Water. Wash-
ington, D.C.: American Chemical Society, 2004.
Havlin, John L., Samuel Tisdale, Werner Nelson, and
James D. Beaton. Soil Fertility and Fertilizers: An Intro-
duction to Nutrient Management. 7th ed. Upper Sad-
dle River, N.J.: Pearson Prentice Hall, 2005.
Web Sites
Agriculture and Agri-Food Canada
Manure, Fertilizer, and Pesticide Management in
Canada
/>afficher.do?id=1178825328101&lang=eng
Economic Research Service, U.S. Department of
Agriculture
U.S. Fertilizer Use and Price
/>See also: Agriculture industry; Eutrophication;
Green Revolution; Guano; Horticulture; Hydropon-
ics; Monoculture agriculture; Nitrogen and ammo-
nia; Potash; Slash-and-burn agriculture; Soil degrada-
tion.
Fiberglass
Category: Products from resources
Fiberglass has many practical uses, especially in struc-

tural applications and insulation, because its fibers
are stronger than steel and will not burn, stretch, rot,
or fade.
Definition
Fiberglass consists offine, flexible glassfilaments or fi-
bers drawn or blown directly from a glass melt. These
fibers may be many times finer than human hair.
Overview
Fiberglass is typically made in a two-stage process.
Glass is first melted and formed into marbles in an
electric furnace, and then fibers are drawn continu
-
ously through holes in aplatinum bushingand wound
Global Resources Fiberglass • 425
onto a revolving drum like threads on spools. The
drum can pull out more than 3 kilometers of fibers in
a minute, and up to 153 kilometers of fiber can be
drawn from one glassmarble that is 1.6 centimeters in
diameter. For a given set of operating conditions, the
size of the fibers is uniform, with diameters varying
from approximately 0.00025 centimeter to 0.00125
centimeter, depending on the application. Some
ultrafine fibers have diameters of 0.0000762 centime-
ter or less. A typical compositionof fiberglass (E glass)
is 54 percent silica, 15 percent alumina, 16 percent
calcia, 9.5 percent boron oxide, 5 percent magnesia,
and 0.5 percent sodium oxide by weight. Because of
its low alkali (sodium) content, this type of fiberglass
has good durability and strength, and because of the
boron, it can be melted at reasonably low tempera-

tures.
Coarse glass fibers were used by the ancient Egyp-
tians to decorate dishes, cups, bottles, and vases. At
the Columbian Exposition in Chicago in 1893, Ed-
ward Drummond Libbey exhibited a dress made of
fiberglass and silk. During World War I (1914-1918),
the Germans produced fiberglass in small diameters
as a substitute for asbestos. In 1938, the Owens-
Corning Fiberglass Corporation was formed in the
United States, and fiberglass production was soon
started on a commercial scale.
Fiberglass wool, made of loosely intertwined strands
of glass with air pockets in between, is an excellent in-
sulator against heat and cold. Itis used asa thermal in-
sulator in the exterior walls and ceilings of homes and
other buildings, as a thermal and electrical insulator
in furnaces, ovens, water heaters, refrigerators, and
freezers, and as a thermal and sound insulator in air-
planes. Fiberglass is commonly combined with plastic
polymers to produce laminates that can be formed
into complex shapes for use in automobile and truck
bodies, boats, carport roofs, swimming pool covers,
and other items requiring light weight, strength, and
corrosion resistance. In addition, fiberglass is woven
into avariety offabrics, tapes,braids, andcords foruse
in shower curtains, fireproof draperies, and electrical
insulation of wire and cable in electric motors, gener-
ators, transformers, meters, and electronic equip-
ment.
Alvin K. Benson

See also: Aluminum; Boron; Glass; Petrochemical
products; Sedimentary processes, rocks, and mineral
deposits; Silicates; Silicon; Textiles and fabrics.
Fires
Category: Environment, conservation, and
resource management
Wildfire is an integral part of wilderness life cycles,
helping keep ecosystems healthy and diverse in plant
and animal life. Controlled human-set fires aid farm-
ers, ranchers, and foresters in making their lands more
productive.
Background
Fire is both inevitable and necessary to most land eco-
systems. Every day, lightning strikes the ground about
eight million times globally, and one stroke in twenty-
five can start a fire. Even so, lightning accounts for
only about 10 percent of ignitions; humans are the
leading agent in setting fires. Fire was one of the first
tools humans used to shape their environment, and it
has remained among the most common tools ever
since. Add tolightning and humans as agents the mol-
ten rock from volcanoes and the sparks sometimes
caused by rock slides, and not surprisingly millions
of hectares of land burn worldwide every year.
Because fire is so prevalent, ecosystemshave evolved
tolerance to it or even a symbiotic dependence on it.
Wildfires foster decomposition of dead material, recy-
cle nutrients, control diseases by burning infected
plants and trees, help determine which plant species
flourish in a particular area, and in some cases even

play arole ingerminating seeds. Purposefully setfires,
today called controlled burns, have flushed game for
hunters since prehistoric times and are still put to
work fertilizing fields and clearing them of unwanted
plants, pruning forests, combating human and ani-
mal enemies, and eliminating dead, dry materials be-
fore they can support a destructive major fire.
Types of Fire
Not all fires are equal. Scientists distinguish five basic
types in increasing order of intensity and destructive
potential: those that smolder in deeplayers of organic
material; surface backfires, which burn against the
wind; surface headfires, which burn with the wind;
crown fires, which advance as a single front; and high-
intensity spotting fires, during which winds loft burn-
ing fragments that ignite separate fires. Moreover,the
intensity, likelihood, and range of fires for any locale
depend upon the climate, season, terrain, weather (es
-
426 • Fires Global Resources
pecially the wind), relative moisture, and time since a
previous burn. The dominant species of plant also af-
fects which type of fire an ecosystem can support.
Tundra and Far-Northern Forests
Fires visit northern ecosystems infrequently because
they retain a great deal of moisture even during the
summer: There are intervals of sixty to more than one
hundred years between fires for forests and several
centuries for tundra. Caused primarily by lightning,
light surface fires are most common. Crown fires are

rare. The seeds of many northern tree species, such as
pine andspruce, germinate well onlyon soil that a fire
has bared. Fire does not occur in high Arctic tundra
and plays only a minor role in the development of low
Arctic tundra.
Grasslands
Grasslands of all kinds rebound from surface fires
in about three years. In shortgrass and mixed-grass
prairies, grass species, especially buffalo grass and
blue grama, survive fires well, while small cacti and
broadleaf plants succumb easily, assuring dominance
of the grasses. For this reason, cattle ranchers fre-
quently burn the prairies to remove litter and inedi-
ble species,thus improving thedistribution of grazing
fodder. In tallgrass prairies, big bluestem, Indian grass,
and switchgrass increase after a fire, whereas cold-
season grasses, such as Kentucky bluegrass, are devas-
tated, and fires prevent invasions of trees and woody
shrubs.
Semidesert and Desert Regions
Similarly, surface fires control shrubs in semidesert
grass-shrub lands on mesas and foothills, while allow-
ing the fire-resistant mesquite to flourish. Desert sage-
brush areas in the intermountain West have a surface
fire about every thirty-two to seventy years. A burned
area takes about thirty years to recover fully, although
horsebrush and rabbitbrush come back quickly.
Global Resources Fires • 427
Wildfires, like this one in 1996 in Calabasas, California, are integral aspects of the natural cycles of life, but too often and increasingly they
encroach on places in which humans dwell. (AP/Wide World Photos)