Mineral Species: Apophyllite & Prehnite

Chemical Formula: KCaSi8O20(F,OH).8H2O & Ca2Al(Si,Al)4O10(OH)2

Chemical Name: Potassium Calcium Silicate & Calcium Aluminium Silicate Hydroxide

Mineral Class: Sheet Silicates

Mineral Notes: Prehnite is a secondary mineral found in in cavities in basalts and similar rocks. It is often associated with zeolites. Prehnite is often found in large massive form, which is often carved for ornamental purposes. 

Description: Very small, but well-formed crystals of white Prehnite located between large glassy crystals of Apohyllite. One of the Apophyllite crystals has a particulalry fine termination, whilst another has a rare hexagonal cross-section.

Location: Thana, Bombay, India.