Chemistry Reference Libraries

Page 10 of about 101 Articles
2005-05-25 11:15:23

The mineral tourmaline is chemically one of the most complicated silicate minerals. It is a complex silicate of aluminium and boron but because of isomorphous replacement (solid solution) its composition varies widely with iron, magnesium and lithium and other elements entering into the combination to a greater or lesser extent. Tourmaline belongs to the trigonal crystal system and occurs as...

2005-05-25 11:09:11

Tungsten (formerly Wolfram) is a chemical element in the periodic table that has the symbol W (L. Wolframium) and atomic number 74. A very hard, heavy, steel-gray to white transition metal, tungsten is found in several ores including wolframite and scheelite and is remarkable for its robust physical properties. The pure form is used mainly in electrical applications but its many compounds and...

2005-05-25 11:04:31

Uranium is a chemical element in the periodic table that has the symbol U and atomic number 92. A heavy, silvery-white, toxic, metallic, and naturally-radioactive element, uranium belongs to the actinide series and its isotope 235U is used as the fuel for nuclear reactors and nuclear weapons. Uranium is commonly found in very small amounts in rocks, soil, water, plants, and animals (including...

2005-05-25 10:55:08

Vanadinite is a mineral with the formula Pb5(VO4)3Cl, lead chlorovanadate. It is part of a series with two other minerals: pyromorphite (Pb5(PO4)3Cl) and mimetite (Pb5(AsO4)3Cl). It has hexagonal crystals, usually prismatic but the crystals are often skeletal or cavernous and it may be found in crusts. It is brittle and has an uneven fracture. The hardness of vanadinite is 2.75-3 and its...

2005-05-25 10:53:46

Vermiculite is a natural mineral which expands with the application of heat. It is formed by hydration of certain basaltic minerals, and is often found in association with asbestos. Mining operations in Libby, Montana were closed in 1990 in response to asbestos contamination. Expanded vermiculite is used as a soil conditioner, as loose-fill insulating and packing material, as an insulating...

2005-05-25 10:34:25

Wollastonite is a calcium inosilicate mineral (CaSiO3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolostone is subjected to high temperature and pressure sometimes in the presence of silica-bearing fluids as in skarns or contact metamorphic rocks. Associated minerals include garnets,...

2005-05-25 10:32:28

Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. Wulfenite is found in many localities, associated with lead ores. It is highly prized by collectors of mineral specimens.

2005-05-25 10:31:05

Zeolites (Greek, zein,"to boil";lithos,"a stone") are minerals that have a porous structure. There are about four dozen recognized naturally occurring zeolite minerals and as many or more synthetic varieties. They are basically hydrated alumino-silicate minerals with an "open" structure that can accommodate a wide variety of positive ions, such as Na+, K+, Ca2+, Mg2+ and others. These positive...

2005-05-25 10:26:23

Zinc is a chemical element in the periodic table that has the symbol Zn and atomic number 30. Notable characteristics Zinc is a moderately reactive metal that will combine with oxygen and other non-metals, and will react with dilute acids to release hydrogen. The one common oxidation state of zinc is +2. Applications Zinc is the fourth most common metal in use, trailing only iron,...

Zircon Dust
2005-05-25 10:17:59

Zircon is a mineral belonging to the group of nesosilicates. Its chemical formula is ZrSiO4. Hafnium is almost always present ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal class. The natural color of zircon varies between colorless, yellow-golden, red, brown or green. Specimens that show gem quality are a popular substitute for diamond (but note that cubic zirconia...

Word of the Day
  • A fool; a simpleton: a term of abuse common in Ireland and to a less extent in the Gaelic-speaking parts of Scotland.
This word is partly Irish in origin.