Calcite forms as stalagmite and stalactites in caves.
Many minerals in the Earth form as white crystals. Often white is one of many possible colors for certain crystals. Most crystals are useful in the manufacture of commercial and household goods. Geologists use properties such as color, luster, shape and hardness to identify crystal types. Some of the most common white minerals today are quartz, calcite, fluorite, gypsum, halite and ulexite.
Quartz is the most abundant mineral on Earth that forms as numerous varieties such as white milky quartz. On the Mohs Hardness Scale of one, soft, through 10, hard, quartz is a seven, meaning that it is hard. Quartz has a glassy luster and is common in many varieties of rocks. Crystals that form with distinct shape as they grow will fracture if struck with force and no longer retain the original shape. Industrial uses of quartz include the manufacture of items such as prisms, lenses, gauges, glass, paint and abrasives.
Calcite is one of the most common and widely occurring minerals on Earth. You can find calcite as the primary mineral in sedimentary rocks such as limestone, and in some igneous rocks. Calcite deposits are also common in caves as stalagmites and stalactites. In addition to white, calcite can be colorless, gray, red, yellow, green, blue, purple or brown. Soft calcite crystals form a rhombic shape, have a glassy luster and are a three on the Mohs Hardness Scale. Calcite is a component in the manufacture of items such as microscopes, building materials and fertilizers.
Ulexite is a unique mineral that people know as TV rock or TV stone. This super soft mineral is a two on the Mohs Hardness Scale and has a silky luster. Famous deposits are located in California, Nevada and Chile. Ulexite has a fiber optic property where a polished crystal is able to transmit images through its silky fibers from the bottom of the sample to the top.
Halite gets its name from the Greek word for salt. Also known as rock salt, samples are typically white to clear in color and can be blue, pink, yellow, red and purple. Halite is very soft, registering only a 2 1/2 on the Mohs Hardness Scale, has a salty taste and a glassy luster. Halite forms good crystals with cubic cleavage and may form as a mass of crystals in a single evaporite deposit.
Gypsum forms as tabular crystals that are soft with a pearly luster. Like halite, gypsum forms as an evaporite mineral. Gypsum also forms as the variety selenite, which has the appearance of white silky crystals strands. Popular locations of gypsum crystals are the United States, Mexico, Italy, Russia, France and Canada. Gypsum has many uses as a component in the production of materials such as paint, tile, drywall, chalk, fertilizer and Plaster of Paris.
Fluorite is a common mineral that comes in many colors in addition to white. Other common colors include blue, red, purple, yellow and green. Fluorite often exhibits color banding. The mineral’s name comes from the Latin word ‘fluere’ that means to flow because fluorite melts more readily than similar minerals. The soft mineral is a four on the Mohs Hardness Scale and has a glassy luster. Fluorite is a component in the manufacture of items such as cooking utensils, hydrofluoric acid, steel and telescopes. Deposits of fluorite exist throughout the world.