Calcite

      The most common of all carbonates, calcite is to discover, because clear crystals or fragments produce a double image of objects viewed through them. Also known as Iceland spar, calcite is used in optical instruments. It is the principal mineral in limestone.

                         Aragonite

         Named for the province of Aragon, Spain, where it was first discovered, aragonite is valuable only as a specimen for collectors. This mineral is fluorescent; it gives off a red or yellow glow when exposed to ultraviolet light.

                           Halite

          Known as rock salt, halite has many applications, but is chiefly used in the chemical industry as a source of sodium and chlorine, and to season foods. Large crystals are used to melt snow on roads and in churning homemade ice cream. The famous dry surface of Searle's Lake in California is covered by a sheet of halite.

                         Fluorite

        Although it occurs in crystal, fluorite is way too soft to be a good gemstone. It is used to promote fusion in the smelting of metallic ores and the manufacturing of steel and hydrofluoric acid.

                            Apatite

         Occurring in many colors, apatite is easily mistaken for fluorite, olivine, aquamarine, and the greenish blue form of beryl. It comes from a Greek word meaning “to beguile.” The most common phosphate bearing mineral, apatite is used to make fertilizers.

                       Quartz

       Easily cut and polished, quartz is one of the most common minerals and a popular source of gemstones. It occurs in a very in a very wide range of colors. Amethyst is the most valuable, but quartz is, also, used to make glass, oscillators, and filters for radios and telephones; and recently, quartz has replaced watch-springs.

                            Talc

        The basic ingredient in talcum powder, talc is widely used as a lubricant and as an insulation in elective equipment. The name is derived from the Arabic word mica, which is similar in certain regards. Massive talc is usually called soup stone.

                     Barite

       This mineral is usually heavy; its density makes it useful in plumbing, the thick mud at oil-well drilling sites; it is also used in the manufacture of paints.

                             Colemanite

         Discovered in Death Valley in 1887, colemanite was named for William T. Coleman, a prominent citizen of early San Francisco and a mine owner. This mineral makes attractive specimens; a source of boron; its comparatively low makes it useful as a flux in the manufacture of glass.

                         Gypsum

       This mineral, gypsum, forms through the evaporation of mineral- enriched waters in lakes and small inland seas.