Mineral Species: Prehnite

Chemical Formula: Ca2Al(Si,Al)4O10(OH)2

Chemical Name: Calcium Aluminium Silicate Hydroxide

Mineral Class: Sheet Silicate

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 crystals of transparent Prehnite upon much larger blocky crystals of Apophyllite. Close inspection also shows small, spherical aggregates of white Phillipsite.

Location: Thana, Bombay, India.