Quartz

Framework silicate

Crystal system: trigonal (+)

Colour in hand specimen: colourless 
Lustre: vitreous 
Pleochroism: none 
Cleavage: none 
Hardness: 7

Colour in plane polarised light: colourless 
Pleochroism: none 
Relief: low 
Birefringence: 0.009; 1^st order grey

M410 Quartz 
Characteristic prismatic crystal form: hexagonal cross-section, needle-like; hexagonal prism surmounted by a hexagonal pyramid 
Colourless, transparent, milky in places 

M411 Quartz 
Madagascar 
Colourless, transparent quartz fragment, milky due to cracks and crystal boundaries 
Vitreous lustre, conchoidal fracture, no cleavage

M412 Quartz (with galena and pyrite) 
North Wales 
A mass of small hexagonal quartz prisms, with galena, pyrite and zinc blende. 
Transparent, white to light grey 
Galena: purple-black, shiny, platy habit, metallic 
Pyrite: metallic lustre, gold colour, cubic habit, “Fools’ gold”

L101 Granite 
L110 Rhyolite, porphyritic (quartz porphyry) 
L120 Granodiorite 
L311 Conglomerate, matrix 
L323 Sandstone, arenite 
L370 Chert, flint nodule, cryptocrystalline 
L504 Garnet schist 
L521 Quartzite