Mineral Species: Schorl

Chemical Formula: Na(Mg,Fe,Mn,Li,Al)3Al6(Si6O18)(BO3)3(OH,F)4

Chemical Name: Sodium Aluminium Borosilicate

Mineral Class: Cyclosilicate

Mineral Notes: Tourmaline is actually a misnomer, describing several closely related, but chemically different, minerals. The variety Schorl is a tourmaline species rich in iron and managenese, which give rise to the dark colouration. Tourmalines are highly sought-after gemstones particulalry when the colour changes along the length of the crystal due to changes in composition during growth. 

Description: A pair of twinned crystals of Schorl, albeit one is much larger than the other. The tops of both have a marked tigonal termination. Any small indentations or cavities are filled with flakes of silver-grey Biotite, which provides an attractive contrast for the black tourmaline.

Location: Doko, Balistan, Pakistan.