Prehnite Ball on Quartz Crystals, on Basalt Matrix - NBB 071

Measurements:  43 x 30 x 23 mm

Description:  A specimen consisting of a prehnite ball (± 15 x 15 mm) sitting on a matrix of clear quartz crystals which, in turn, sit on a thin matrix of basalt rock. On closer examination, it looks like two balls of prehnite that had fused together to form one.

Apart from limited damage to the edges of the specimen, there are only a few extremely minute nicks (hardly visible to the naked eye) to a few of the lesser quartz crystals.

Weight of Specimen:  23.1 g  

Chemical Composition:   Ca₂Al₂Si₃O₁₀(OH)₂    (prehnite)  
                                        SiO₂  (quartz)  
                                        CaCO₃  (calcite) 
                                 
Hardness on Mohs Scale:   (prehnite) 6-6.5
                                           (quartz)  7                                                                                             (calcite)  3 

Location:  Brandberg, Namibia.

Specimen Code:  NBB 071

US $ 55