Quartz

Quartz single crystal, no cleavage, conchoidal fracture.

Quartz prisms, vitreous lustre.

Quartz prisms (roughly hexagonal habit).

Quartz crystal structure (trigonal unit cell), CrystalMaker.

Formula

SiO₂

Structure

Framework silicate

Crystal System

Crystal system: trigonal (+)

Physical Properties

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

Optical Properties

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

Mineral Specimens

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”

Rock Specimens

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

Mineral Name

silica
quartz