Chemistry Reference Libraries
The annual herb, Borage, better known as Starflower, originated in Syria, but has been naturalized throughout the Mediterranean region, in addition to Asia Minor, Europe, North Africa and South America. The plant grows to heights of about 2 to 3 feet with bristly stems and leaves. The leaves themselves are alternately arranged and simple, and measure between 2 and 6 inches long. Five...
Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. In chemical composition and general characteristics they are very similar to the pyroxenes and, like them, fall into three series according to their system of...
Aragonite is a polymorph of the mineral calcite, both having the chemical composition CaCO3. Its structure differs from calcite and leads to a different crystal shape, an orthorhombic system with acicular crystals. By repeated twinning pseudo-hexagonal forms result. It may be columnar or fibrous, occasionally in branching stalactitic forms called flos-ferri (flowers of iron) from their...
Asbestos (Greek a-, "not"; sbestos, "extinguishable") is a group of fibrous metamorphic minerals. The name is derived for its historical use in lamp wicks; the resistance of asbestos to fire has long been exploited for a variety of purposes. It was used in fabrics such as Egyptian burial cloths and Charlemagne's tablecloth, which, according to legend, he threw in a fire to clean. When...
Augite is a mafic mineral described chemically as (Ca, Na)(Mg, Fe, Al)(Al, Si)2O6 or calcium sodium magnesium iron aluminium silicate. Structurally, it is a solid solution of the pyroxene group which also contains diopside and hedenbergite. The crystals are monoclinic and prismatic. It is found in igneous rocks such as gabbros and basalts, and in metamorphic rocks from hydrothermal vents....
Aurichalcite is a mineral, usually found as a secondary mineral in copper and zinc deposits. Its chemical formula is (Zn,Cu)5(CO3)2(OH)6. The name probably originates from the Greek oreichalchos meaning "mountain copper".
Autonite (Hydrated Calcium Uranyl Phosphate) is a yellow - greenish fluorescent mineral with a Hardness of 2 - 2½. Due to the high content in uranium, it is radioactive and also used as uranium ore. If the mineral dries out, it converts to meta-autunite-I, which can turn into meta-autunite-II after heating. These two subsequent minerals are very rare in nature. For scientific studies it is...
Azurite is a carbonate mineral with chemical composition Cu3(CO3)2(OH)2, (copper carbonate hydroxide). Azurite is often found in association with the green mineral malachite as a result of the weathering and oxidation of copper sulfide minerals. The name azurite comes from the Arabic word for blue. Azurite is used in jewelry and also collected as a beautiful mineral specimen. Use as a...
Barite (BaSO4) is a mineral consisting of barium sulfate. It is generally white or colorless, and is the main source of barium. Baryte is the British spelling. The radiating form is also sometimes refered to as Bologna Stone. Barite commonly occurs in lead-zinc veins in limestones, in hot spring deposits, and with hematite ore. It is often associated with the minerals anglesite and...
Bauxite is a naturally occurring, heterogeneous material composed primarily of one or more aluminium hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminosilicate, and other impurities in minor or trace amounts. The principal aluminium hydroxide minerals found in varying proportions with bauxites are gibbsite and the polymorphs boehmite and diaspore. Bauxites are...
