Oxides

Oxides

One of the most common minerals, goethite is typically formed as a weathering product of iron-bearing minerals. It was named for the German poet, novelist, playwrite, philosopher and geoscientist Johann Wolfgang von Goethe (1749-1832). It is used as an ore of iron.

A slightly magnetic mineral, franklinite was named in honor of Benjamin Franklin, American statesman, and the locality of Franklin Furnace, New Jersey, which was named after him as well. It is used as an ore of zinc and manganese. The zinc is converted into zinc white and the manganese is used in the manufacture of steel.

Discovered in 1801, this mineral’s name is derived from a Greek word meaning "to scatter", in allusion to its decrepitation (emit a crackling sound) when heated. It occurs with other minerals in bauxite deposits and is used as a refractory.

Named in 1845 from the Latin cuprum in allusion to its composition, this mineral is a minor ore of copper. It is a supergene copper mineral found in the upper oxidized portions of copper veins. It comes in various shades of red with the transparent crystals being called "ruby copper".

This mineral’s crystals commonly occur as barrel shapes with deep horizontal striations. It is common as an accessory mineral in silica poor rocks, and is frequently found in detrital soil and stream sands due to its hardness. The red gem variety is called ruby, one of the most valuable of gems. The blue gem variety is called sapphire.

Discovered in 1928 in Columbia (a name for America), this mineral occurs in granitic rocks and pegmatites. It is a source of the rare earth element niobium, which is used in alloys in weldable high-speed steels, stainless steels, and alloys resistant to high temperatures.

Chrysoberyl is a rare mineral that occurs in granitic rocks and pegmatites and in mica schists. Used as a gemstone, the varieties, alexandrite and cat's eye, are highly prized. The name comes from the Greek meaning “golden” and beryl, in allusion to the color. It was discovered in Brazil in 1789.

The only ore of chromium, chromite is a major constituent in stainless steel. It is one of the first minerals to separate from a cooling magma, and large chromite deposits are thought to have been derived by such magmatic differentiation.

The mineral name is derived from the term “Cassiterides," which was applied to an island off the western coast of Europe in pre-Roman times. The primary ore of tin, this mineral is found in hydrothermal veins and pegmatites associated with granite intrusions. The chief use of tin is in the manufacture of tin plate and tern plate.

Discovered in 1824, this mineral was named after Archibald Bruce (1777-1818), an early American mineralogist, who first described the species. It can be identified by its foliated nature, light color, and pearly luster on cleavage face. It can be distinguished from mica by being inelastic.