Acicular Natrolit from India

Natrolite is a tectosilicate mineral species belonging to the zeolite group.

Formula: Na2Al2Si3O10 · 2H2O
System: Orthorhombic
Colour: White, Colorless, Red, …
Hardness: five – 5½
Member of: Zeolite Group

Needle rock or needle-zeolite are other informal names, alluding to the mutual acicular habit of the crystals. 
From Nasik District, Maharashtra, India