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”
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”