Aurichalcite 
 
Locality: General Thomas Mine, Lone Mountain Mining District, Esmeralda County, Nevada, USA

Size: 35 mm x 28 mm, 26 grams
 
A lovely specimen of lovely light blue Aurichalcite on matrix.
 
Aurichalcite is a rare secondary mineral found in some Copper and Zinc deposits. It is normally light blue in colour but greener specimens are also know. Aurichalcite is found in fine acicular crystals forming mats or crusts.