Mineral Species: Richterite

Chemical Formula: Na3(Mg,Fe)4Si8O22(OH)2

Chemical Name: Sodium Calcium Magnesium Iron Silicate Hydroxide

Mineral Class: Inosilicate

Mineral Notes: Richterite belongs to a group of minerals called the Amphiboles. These are double chain silicates where the chains are held together by metal ions such as Magnesium and Aluminium, and occassionally more exotic metals such as Manganese or Titanium. It has almost identical composition to Tremolite except that the principal metal ion is Sodium instead of Calcium. For this reason Richterite is often called Soda Temolite. Richterite is a rare mineral, but is found throughout the world as a constituent of unusual rocks, for example, in contact metamorphosed limestones.

Description: A brown matrix embedded with lustrous, brown Richterite crystals. Whilst most are intergrown or twinned, there are numerous single crystals as well. These are generally flattened, elongated prisms. A few are very lustrous and quite gemmy.  

Location: Lanban Mine, Filipstad, Varmland, Sweden.