Apatite

Non-silicate

Crystal system: hexagonal (-)

Colour in hand specimen: green, white, yellow, blue brown etc.
Hardness: 5

Colour in plane polarised light: generally colourless
Pleochroism: weak to moderate in coloured varieties
Relief: moderate
Birefrinence: 0.001-0.007; first order greys
Extinction: straight
Form: commonly hexagonal in cross-section

L100 Alkali granite 
L101 Granite 
L120 Granodiorite 
L130 Andesite, porphyritic (porphyrite)