Rhodonite

Hardness: 5.5-6.5 on Mohs scale; Color: Rose-pink to reddish-brown, often with black dendrites or veins of manganese oxides; Luster: Vitreous to pearly; Crystal Structure: Triclinic; Cleavage: Perfect on two directions; Specific Gravity: 3.4-3.7

Rhodonite typically forms in metamorphic rocks under high-pressure and moderate-temperature conditions, often associated with manganese deposits. It can also be found in contact metamorphic zones and hydrothermal veins. Its geological age varies depending on the specific deposit, but it is found in formations ranging from Precambrian to relatively recent.

Rhodonite is primarily used as an ornamental stone and in jewelry for beads, cabochons, carvings, and polished slabs. Due to its attractive pink color, it is popular for decorative items. Smaller quantities may be used as an ore of manganese, though it is not a primary source.

The name Rhodonite comes from the Greek word 'rhodon', meaning rose, referring to its characteristic pink color. It is the official state gem of Massachusetts, USA. Historically, it was sometimes used as a flux in glassmaking due to its manganese content, which can impart purple hues to glass.

In the field, Rhodonite is identified by its distinctive rose-pink to reddish color, often with black manganese oxide inclusions (dendrites or veins), and its relatively high hardness. It is commonly found in Sweden (where some of the finest specimens come from), Russia (Urals), USA (Massachusetts, Colorado), Australia, South Africa, and Brazil. Collectors look for vibrant pink colors and interesting patterns of black inclusions. Be cautious not to confuse it with Rhodochrosite, which is softer and typically has white banding, or Thulite, which is a massive pink variety of zoisite.