Non-silicate

Crystal system: cubic

Colour in hand specimen: pale brassy yellow; black when fine-grained
Streak: greenish or brownish
Lustre: metallic
Cleavage: not obvious
Hardness: 6-6.5

Colour in plane polarised light: opaque

M520 Slate containing pyrite
Coniston, Lancashire 
Cubic crystals, embedded in a well-cleaved slate 
Golden colour 
Metallic lustre 
Indistinct cleavage in places

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”

L112 Rhyolite 
L371 Chert, bedded