Wednesday, March 4, 2009

March 2009 Mineral of the Month


The name Rhodochrosite comes from the Greek, rhodom, meaning rose and chrosis meaning a coloring refering to it's color. Rhodochrosite commonly occurs as a primary gangue mineral in moderate to low temperature hydrothermal veins also in high temperature metasomatic deposits and sedimentary manganese deposits or more rarely as a late stage hydrothermal mineral in pegmatites.

This mineral sometimes forms as rhombohedral, scalenohedral, prismatic or tabular crystals. More often, rhodochrosite occurs in massive, granular, stalactitic, glogular, nodular or botryoidal habits.

Its color is typically pink to red though it may also be brown, orange or yellowish. Manganese is what gives rhodochrosite its vivid pink to red color. The streak is white. It is transparent to translucent and has a vitreous to pearly luster.

It is a member of the carbonates family and its chemical composition is MoCO3. It is very soft coming in at 3-1/2 to 4 on the Moh's Scale. Its specific gravity is 3.7 and has an uneven fracture. Its cleavage is perfect rhombohedral.

Rhodochrosite is soluble in warm hydrochloric acid with effervescence.