Mineral description : Quartz

Rock crystals from Granmuren.
Amethyst crystals from Långsjön.
Rock crystals from Hattfjelldal, Norway.
Jaspis and white quartz from Långban.
Rose quartz from Ytterklippen.
Aventurine quartz from Northern Finland.

Mineral class Silicates : Quartz - Opal group.
Chemical formula SiO2
Crystal system Trigonal.
Habitus As hexagonal prisms with rhomboedric terminations. Also common in dense masses or grainy aggregates.
Cleavage Conchoidal.
Hardness 7
Density 2.65
Color Usually white or colorless, but also exists in yellow, purple, pink, green, blue, gray or black.
Streak Colorless to white.
Luster Vitreous on crystals, greasy in massive.
Description Quartz is one of the most commonly minerals on the Earth. It have several industrial uses, for example as a main part in glas or as the base for manufacturing silicon wafers for the electronics industry.
Occurance In many different rocks as igneous, metamorphic and sedimentary. As a main part in pegmatites and hydrothermal veins.
Associates  
Notes Some variants of quartz are :
  • Rock crystal : Another name of clear colorless quartz crystals.
  • Milky quartz : White from water inclusions in the crystal.
  • Rose quartz : Pink from manganeese and titanium.
  • Jaspis : Red from microscopic inclusions of hematite.
  • Aventurine : Green from goethite and mica (not known from Sweden).
  • Amethyst : Purple from iron.
  • Citrine : Orange to yellow from colloidal iron hydroxide.
  • Blue quartz : Blue by microscopic tourmaline inclusions, or other inclusions.
  • Smoky quartz : Black by irradiation (destroyed crystal lattice).
Locations A very common mineral, a few localities are :
Milky quartz :
  • Commonly in most of the pegmatite quarries in Sweden.
Rock crystal :
  • Blåkullaberg, Smedjebacken, Dalarna. As 2-3 cm crystals.
  • Olden and Västsjön, Offerdal, Jämtland. In fractures in clay schist.
  • Vassijauri, Lappland. As crystals in druses and fractures.
  • Dannemora, Grängesberg and Gärdsjö, Värmland. And many more mines.
  • Insjö mine. As small crystals on the dump pile.
  • Nasafjäll silver mine. As crystals together with boulangerite.
Smoky quartz :
  • Hesselkulla iron mine, Närke. Up to 7 cm crystals with coarse calcite.
  • Mejdåsen quartz quarry, Björbo, Dalarna. As dull and iron stained crystal aggregates.
  • Drömgruvan, Kolmorden. Massive.
  • Varuträsk pegmatite. Massive.
  • Riddarho, Värmland. Massive.
  • Kaatiala pegmatite, Finland. Massive.
Rosy quartz :
  • Mossbodarna quartz quarry, Överhogdal, Härjedalen. Massive.
  • Hoting quartz quarry, Ångermanland.
  • Drömgruvan quartz quarry, Kolmården.
Amethyst :
  • Lake Ärten, Sågen, Dalarna. Massive or as small crystals in brecciated sand stone. It is not allowed to collect there any longer.
  • Långsjön, Surahammar, Västmanland. As crystals in fractures in granite.
  • Ramsätershöjden, Värmland.
Citrine :
  • Dannemora mines, Uppland. Sporadic as small crystals.
  • Ställdalen, Västmanland. Crystals in loose boulders.
Blue quartz :
  • As small blue grains in many metamorphic rocks.
  • Mossbodarna quartz quarry, Överhogdal, Härjedalen. Massive together with rosy quartz.
  • Skellefteå mining district. In granites.
Jaspis :

To silicate index.
Mineral group index.
Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.


axelsson@acc.umu.se
To my homepage.
Last changed : 2004-01-28