Zeolites are a group of silicate minerals with unusual properties with industrial importance. They usually form beautiful well-formed crystals with pale colors, and are relatively soft and can be crushed and powdered. They are found in geologically young volcanic fields. Most common zeolite minerals are analcime, chabazite, clinoptilite, mordenite, natrolite, heulandite, phillipsite and stilbite.
The term talc refers both to the pure mineral and a wide variety of soft, talc-containing rocks that are mined and utilized for a variety of applications. Talc forms mica-like flakes. Talc is the softest mineral on the Mohs hardness scale at 1 and can be easily cut and crushed. Talc has perfect cleavage in one direction. This means that it breaks into thin sheets. As a result, it feels greasy to the touch (which is why talc is used as a lubricant).
Also called silica sand or quartz sand, silica is silicon dioxide (SiO2). Silicon compounds are the most significant component of the Earth’s crust. Since sand is plentiful, easy to mine and relatively easy to process, it is the primary ore source of silicon. The metamorphic rock, quartzite, is another source.
Silicon (Si) is a semi-metallic or metalloid, because it has several of the metallic characteristics. Silicon is never found in its natural state, but rather in combination with oxygen as the silicate ion SiO44- in silica-rich rocks such as obsidian, granite, diorite, and sandstone. Feldspar and quartz are the most significant silicate minerals. Silicon alloys include a variety of metals, including iron, aluminum, copper, nickel, manganese and ferrochromium.
Halite, commonly known as table salt or rock salt, is composed of sodium chloride (NaCl). It is essential for life of humans and animals. Salt is used in food preparation across the globe.
Rutile is the most common and stable form of titanium dioxide found in nature. It forms under high pressure and high temperature in igneous and metamorphic rocks. It is a key ingredient in paint and also a useful component in optical equipment.
Quartz is one of the most common minerals in the Earth’s crust. As a mineral name, quartz refers to a specific chemical compound (silicon dioxide, or silica, SiO2), having a specific crystalline form (hexagonal). It is found in all forms of rock: igneous, metamorphic and sedimentary. Quartz is physically and chemically resistant to weathering. When quartz-bearing rocks become weathered and eroded, the grains of resistant quartz are concentrated in the soil, in rivers, and on beaches. The white sands typically found in river beds and on beaches are usually composed mainly of quartz, with some white or pink feldspar as well.
Commonly called fool’s gold, pyrite is the Earth’s most abundant sulfide mineral. Recognized for its brass-yellow color which resembles that of gold, pyrite is a source of iron and sulfur and is used for the production of sulfuric acid. Some types of pyrite contain enough microscopic gold to warrant mining them as a gold ore.
Mica is a mineral name given to a group of minerals that are physically and chemically similar. They are all silicate minerals, known as sheet silicates because they form in distinct layers. Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible. Mica is heat-resistant and does not conduct electricity. There are 37 different mica minerals. The most common include: purple lepidolite, black biotite, brown phlogopite and clear muscovite.
IMAR 7th Edition
Kyanite, andalusite, and sillimanite are naturally occurring anhydrous aluminum silicate minerals. Each has the same chemical formula, Al2SiO5, but differing crystal structures, making them mineral polymorphs. These variances in crystal structure give somewhat unique physical properties to each of the three minerals, and each is used in slightly different ways by modern industry. Mullite is a very rare mineral named for its discovery site on the Scottish Isle of Mull.
Mullite, although seldom found in nature, can be artificially produced by heating any number of aluminum silicate minerals in certain proportions to the correct temperature.
Kyanite is a blue to light-green, triclinic mineral that occurs in long, thin-bladed crystals and crystalline aggregates in gneiss, schist, and pegmatites.
Andalusite is a yellow, brown, green, or red orthorhombic mineral that occurs in thick, almost green prisms in schist, gneiss, and hornfels. Gem-quality andalusite exhibits a strong pleochroism— brownish-green in one direction and brownish-red perpendicular to it. Andalusite also occurs in placer concentrations where it has weathered out of rock.
Sillimanite is a brown, pale-green, gray, or white orthorhombic mineral that occurs in long, slender, needlelike crystals in schist and gneiss.
Kaolinite is a layered silicate clay mineral which forms from the chemical weathering of feldspar or other aluminum silicate minerals. It is usually white, with occasionally a red color impurity due to iron oxide, or blue or brown from other minerals. Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity, making it ideal for many industrial applications.