Silky white acicular crystals of the rare mineral rhodesite on a contrasting matrix. From Trinite Claim, Wildcat Peak, Trinity County, California, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Rhodesite
Rhodesite is an IMA-recognized mineral species in the silicate class, with the chemical formula KHCa₂Si₈O₁₉·5H₂O.
It crystallizes in the orthorhombic crystal system (space group Pmmn). It is a member of the Rhodesite structural group.
Key properties: Mohs hardness 4; specific gravity 2.27–2.36; Silky luster; optically biaxial.
IMA symbol Rod, grandfathered status — known before the IMA’s founding, named in 1957.
Found in a kimberlite pipe (Kimberley, South Africa); in a magadiite deposit localized in altered silicic lavas (Trinity Co., California, USA).
It is found associated with Mountainite (Kimberley, South Africa); magadiite, montmorillonite (Trinity Co., California, USA).
The name refers to Cecil John Rhodes (1853–1902), British founder of the DeBeers Mining Company, also for Rhodes University, Grahamstown, South Africa, where the mineral was examined.