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: Small, irregular crystals of pale green Prehnite sitting between well-formed cubes of Apophyllite. Some of the Apophyllite crystals are twinned, giving rise to interesting forms. The contrast between the green Prehnite and white Apophyllite is very attractive.

Location: Thana, Bombay, India.