GOLD, Au, is the most malleable and ductile of all the noble-metals and very heavy native alloy.
PLATINUM, Pt, a heavy grayish-white non-corroding precious metallic element. Malleable and ductile, fusible with difficulty, and resistant to most chemicals, dissolves slowly in aqua regia, (aqua regia, a mixture of nitric and hydrochloric acids, which will dissolve gold or platinum.)
SILVER, Ag, a white metallic element, sonorous, ductile, very malleable and capable of high degree of polish. It has the highest thermal and electric conductivity of any substance.
TANTALUM, Ta, a hard, ductile, gray-white, acid-resisting metallic element, with difficulties in isolating it; found in tantalite, columbite, and other rare-earth minerals.
WOLFRAMITE, WO , a Tungstate of iron and manganese (Fe, Mn), a brownish or grayish-black color and sub-metallic luster; also called wolfram. It occurs in monoclinic crystals and in granular or columnar masses. It is a source of tungsten.
CASSITERITE, native tin dioxide, SnO ; a dark-colored mineral, chief source of metallic tin. H., 6-7. Sp. gr., 6.8-7.1.
COLUMBITE, Fe-(Cb,O ) , a native black compound of iron and columbium, often containing manganese and grading into tantalite.
COLUMBIUM, Cb a steel-gray, lustrous, metallic element, also known as NIOBIUM, Nb.
SCHEELITE, CaWO , native calcium tungstate, a source of tungsten.
MONAZITE, PO , phosphate of the cerium metals, essentially (Ce,La,Nd,Pr.)PO.
HEMATITE, an important ore of iron, (Fe ,O ) red when powdered.
MAGNETITE, an iron oxide (Fe O ) an important ore, sometimes possessing polarity, being then called loadstone.
ZIRCON, a silicate of zirconium, ZrSiO , a tetragonal mineral occurring usually in square brown or grayish prisms or pyramids. Transparent varieties are used as gems.
CHROMITE, a mineral of the spinel group composed of iron, chromium and oxygen, FeCr O , valuable as a source of chromium. (Spinel, a hard mineral consisting of magnesium and aluminum, and of van'ous colors, the red variety being the gem spinel ruby.)
RUTILE, a mineral consisting of titanium dioxide, TiO , usually of a reddishbrown color and brilliant metallic luster; usually contains a little iron.
DIAMOND, native crystallized carbon, highly valued when free of flaws as a precious stone; 1 metric carat - 200 milligrams = 3.086: grains = .2 gram.
