Rhodochrosite
Introduction
Rhodochrosite is a manganese carbonate mineral with the chemical composition MnCO3. The mineral is typically pink or red, owing to the presence of manganese, but can also be brown or gray. It is often banded in layers of varying shades of pink and white, and can also occur as stalactites and stalagmites in caves. Rhodochrosite is a relatively soft mineral, with a Mohs hardness of 3.5-4. It is named after the Greek words "rhodon" and "chros", meaning "rose colored".
Physical Properties
Rhodochrosite has a vitreous to pearly luster and is translucent to transparent. Its specific gravity is 3.7, which is above average for minerals. This means that a given volume of rhodochrosite is heavier than the same volume of many other minerals. The mineral has perfect cleavage in three directions, which means that it breaks along flat planes. This property is a result of the structure of the mineral's crystal lattice.
Chemical Properties
Rhodochrosite is a carbonate mineral, which means it contains the carbonate ion (CO3). It is a member of the calcite group of minerals, which also includes minerals such as calcite and aragonite. Rhodochrosite's pink color is due to the presence of manganese ions in the crystal structure. The mineral can also contain minor amounts of iron, calcium, and magnesium. When heated, rhodochrosite will decompose to produce manganese oxide and carbon dioxide gas.
Occurrence and Formation
Rhodochrosite is found in hydrothermal veins and pegmatites, and is often associated with silver, lead, and zinc ores. It can also occur in large quantities in sedimentary manganese deposits. The mineral is found in many parts of the world, but significant deposits exist in Argentina, Peru, Colorado in the United States, and Romania. The Sweet Home Mine in Colorado is particularly famous for producing rhodochrosite specimens of exceptional quality and size.
Uses and Applications
Due to its attractive color and banding, rhodochrosite is often used as a gemstone and ornamental stone. High-quality specimens are cut into cabochons or beads for jewelry, while lower-quality material is often carved into decorative objects. Rhodochrosite is also a popular mineral among collectors. In addition, the mineral is an important ore of manganese, which is used in the manufacture of steel and other alloys.