Rocks and Minerals Gallery
Galena
Composition: Lead sulfide. May contain impurities, such as silver, arsenic, antimony, and copper.
Uses: Galena is by far the greatest ore of lead. Galena is the most common mineral containing lead, and contains mostly lead. Since the extraction process is so simple, lead has been extracted from Galena since the earliest times. Galena was also used in early radio devices. Well crystallized Galena specimens are popular collectors items.
Galena from certain regions is rich in silver. Specimens may contain as much as 20 percent silver. Because of this, silver-rich Galena is commonly an ore of silver.
Gypsum
Composition: Hydrous calcium sulfate
Uses: Gypsum is an industrially important mineral. It is the primary ingredient of plaster-of-Paris (finely ground Gypsum) and is also used in the production of cement. It is also the main component of sheet-rock. It is used as a flux for creating earthenware, and can be used as a fertilizer. The variety Alabaster is is carved for ornamental use, such as artistic sculptures and pottery. It is porous and is therefore easily dyed. The fibrous Satin Spar variety is sometimes cut into cabochons for collectors because of its strong cat's eye effect.
Fine Gypsum specimens are very popular among mineral collectors, especially the varieties Selenite and Desert Rose.
Hematite
Composition: Iron oxide. May contain slight amounts of titanium.
Uses: Hematite is the principle ore of iron. Huge quantities are mined yearly for industrial production. It is the source for roughly 90 percent of all iron mined in the United States. Hematite was largely used in the past as a red and brown pigment, although nowadays cheaper sources have been substituted. Well formed Hematite crystals are popular among mineral collectors. Highly polished, tumbled Hematite from Brazil makes a very popular, inexpensive specimen for collectors. Hematite also has gem uses. It is cut and polished into cabochons for jewelry and ornaments, fashioned into beads for bracelets and necklaces, and carved into ornamental figures.
Magnetite
Composition: Iron oxide. May contain many impurities partially replacing both the first and the second iron.
Uses: Magnetite is an important ore of iron. Its perfect crystals are also famous among mineral collectors. This mineral is of scientific interest because of its special magnetic properties.