Most elements need to be concentrated into amounts that
can be economically mined from ore deposits (usually hundreds to thousands of times
their crustal abundance). This concentration is usually accomplished by
dissolution of the element by hot water (hydrothermal ore deposits - gold,
silver, lead), preferential crystallization from magmas (chromite deposits or
pegmatites), surface weathering and leaching (aluminum, nickel, copper), or
gravity separation of minerals during erosion (gold, diamonds, titanium). In the majority of cases there are only one or two
minerals that provide all of a particular element for commercial uses. Some
elements in low concentrations (substituting in minor amounts for the major
elements) are associated with minerals that are mined for other elements, but
the shear volumes of materials that are processed result in a valuable byproduct
(i e. elements associated with copper, lead, and zinc ores). Some elements are so
valuable that almost any mineral containing that element in sufficient grades
can be mined (gold, silver, platinum group).
Aluminum - The ore is mined from rocks that have been exposed to
weathering in a tropical environment, bauxite. The main ore minerals in
bauxite are gibbsite, bohmeite, and diaspore.
Antimony - The primary ore of antimony is it's sulfide, stibnite.
Arsenic - Recovered from other metal processing streams (primarily
from the sulfosalts such as tennantite etc.). Arsenopyrite
is the most common arsenic mineral. The relatively low demand for arsenic as
compared to the amount of arsenic mined that is associated with other metals
means it can be supplied from the waste streams of other ore processing.
Barium - The chief source of barium is barite with minor production of
Beryllium - The major ore mineral for beryllium in the U.S. is bertrandite
while worldwide the major source is from pegmatites that contain beryl.
Bismuth - Primarily a byproduct of lead processing. Also found in a
number of minerals such as bismuthinite and as a constituent in various sulfosalts.
Boron - Chief source is playa lake deposits of borax, colemanite,
Bromine - Chief sources are brines from wells and Dead Sea.
Cadmium - Unlike
many other commodities cadmium is produced as a byproduct of zinc (sphalerite) mining.
Cesium - The major
ore mineral is pollucite, a pegmatite mineral. Production and use of this metal
is extremely small (a few thousand kilograms per year).
Chlorine - Produced
from the mineral halite (rock salt).
Chromium - The chief
source is the mineral chromite which is found in large layered intrusives and
Cobalt - The primary
minerals for cobalt is cobaltite. Some cobalt is also produced from weathered
Columbium (see Niobium)
Copper - Most copper
ore bodies are mined from minerals created by weathering of the primary copper
ore mineral chalcopyrite. Minerals in the enriched zone include chalcocite, bornite,
djurleite. Minerals in the oxidized zones include malachite, azurite,
chyrsocolla, cuprite, tenorite, native copper and brochantite.
Gallium - A
byproduct of zinc and alumina processing. Some primary "ore" may
contain up to 200 ppm. Ga.
Germanium - A
byproduct of zinc ore processing. Also a deposit in China is associated with coal.
Gold - The primary mineral
of gold is the native metal and electrum (a gold-silver alloy). Some tellurides are also important ore minerals
such as calaverite, sylvanite, and petzite.
Hafnium - Primary
ore mineral is zircon.
Indium - Primarily
is a byproduct of zinc processing.
Iodine - Initial
production was from seaweed. Iodine is extracted from natural gas field brines
(up to 1200 ppm iodine in the brines).
Iron - Two major
minerals in the production of iron are it's oxides, hematite and magnetite.
These are found in preCambrian iron formations. Historically there was also
production from goethite and siderite. The iron sulfides (pyrite and pyrrhotite)
were not used as iron
sources due to the difficulty of removing sulfur from the metals and the
brittleness this sulfur caused in the metal.
Lead - The primary
for lead is it's sulfide - galena. Some minor production from the past has come
from secondary lead minerals - cerussite and anglesite.
Lithium - The former
primary ore minerals were pegmatite deposits of spodumene, lepidolite, and petalite,
the major U. S. production is from lithium carbonate brines.
Magnesium - Although
magnesium is found in many minerals, only dolomite, magnesite, brucite,
carnallite, and olivine are of commercial importance. Magnesium and other
magnesium compounds are also produced from seawater, well and lake brines and
Manganese - The
primary ores are oxides/hydroxides of manganese which include minerals such as
hausmannite, pyrolusite, braunite, manganite, etc. and the carbonate, rhodochrosite. A large potential source is the deep sea
Mercury - The main ore is
the sulfide, cinnabar.
Molybdenum - The primary
ore mineral is molybdenite.
Nickel - The primary
nickel ores are pentlandite, nickel bearing pyrrhotite and a weathering product,
garnierite (a mixture of népouite, pecoraite and willemseite).
- The primary ore mineral is pyrochlore with minor columbite and tantalite-columbite.
Phosphorus - Main
ore minerals are in the apatite group of minerals (hydroxylapatite, fluorapatite,
(Platinum, Osmium, Rhodium, Ruthenium, Palladium) - The primary ores are
the native elements or alloys of the various elements or arsenides such as
sperrylite. They tend to occur in
layered intrusives associated with chromite deposits.
Potassium (potash) -
The primary ore minerals are sylvite (primarily), brines, and langbeinite.
Rare Earth elements
(cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanium,
lutetium, neodymium, praseodymium, samarium, scandium, terbium, thulium, ytterbium,
yttrium) The major ore minerals
containing rare earth elements are bastnasite, monazite, and loparite and the
lateritic ion-adsorption clays. Major U.S. production of bastnesite is from
Mountain Pass, California.
Rhenium - Produced
as a byproduct of molybdenite.
Substitutes for potassium in lepidolite and pollucite. Production is small (a
few thousand kilograms per year).
Scandium (see Rare Earth)
Selenium - Recovered
from copper processing.
Silicon - The
primary source is quartz.
Silver - Silver production
has been from the sulfide argentite/acanthite, native silver, sulfosalts such as pyrargyrite
and proustite, chloride as cerargyrite. It is also found in small amounts in
Sodium - Principle
resources are halite (rock salt) or soda ash (see below).
Strontium - Main ore
mineral is celestite, with minor production of strontianite.
Sulfur - Major
production is from desulferizing natural gas and petroleum. Sulfuric acid is
the flue gases of metal smelters. Historically, sulfur was produced from native sulfur
Tantalum - Primarily
from tantalite-columbite although minor amounts are found in tin concentrates.
Recovered in processing copper ores.
Thallium - Recovered
from processing copper, lead and zinc ores.
Thorium - Recovered
primarily from monazite.
Tin - Primary ore is
Titanium - Usually
produced from placer deposits, the ore minerals are rutile, ilmenite, and leucoxene.
Tungsten - Primary
ore minerals are scheelite and huebnerite-ferberite.
Uranium - The chief
primary ore minerals are uraninite, pitchblende (a mixture of various oxides),
coffinite and a
host of secondary minerals such as carnotite and autunite.
Vanadium - Recovered
from petroleum residues also produced from vanadium bearing magnetite rocks. In
the past it was recovered from minerals in uranium deposits.
Zinc - The primary zinc
ore mineral is sphalerite, zinc sulfide. Some past production has been from
smithsonite and hemimorphite.
Zirconium - Major
source is the mineral zircon.
Abrasives, natural -
Diamonds, garnets (almandine, pyrope and andradite), corundum (emery).
Barite - A major use for barite is as a weight increasing additive for
drilling oil and gas wells.
Calcite - A major
source for this mineral is limestone. It has been used for the manufacture of
cement, application to agricultural lands for pH control, as a building
material, and crushed for gravel.
Clays - Used in the
manufacture of bricks, tiles and as a filler for paper etc.