Mineralpedia Details for Gonyerite

Named for Forest A. Gonyer, an analytical chemist in the Department of Mineralogy and Petrography at Harvard University in Massachusetts, USA. Gonyerite is a rare mineral that gets its type locality from Langban, Sweden, and has additional localities in South Africa, the United States, Norway, Italy, and Germany. Gonyerite occurs in hydrothermal veins through skarn.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/gonyerite.pdf

Formula

Mn²⁺₅Fe³⁺(Si₃Fe³⁺)O₁₀(OH)₈ 

Crystal System

Orthorhombic 

Crystal Habit

Radial, Platy 

Cleavage

Perfect, None, None 

Luster

Pearly 

Color

dark brown, brownish black, bright green 

Streak

chocolate brown 

Class

Orthorhombic 

Fracture

Flexible 

Hardness

2.5 

WebMineral

View Gonyerite 

Mindat

View Gonyerite 

Dark brown or bronze colored rosettes as silky looking radiating sprays to 5mm in diameter.

Deep reddish, platy crystals to 2mm in radial patterns in matrix.