Quartz crystal is one of several minerals which are piezoelectric, meaning that when pressure is applied to quartz, a positive electrical charge is created at one end of the crystal and a negative electrical charge is created at the other. These properties make quartz valuable in electronics applications. Electronics-grade manufactured quartz is used in a large of circuits for consumer electronics products such as computers, , televisions, radios, electronic games, etc. It is also used to make frequency control devices and electronic filters that remove defined electromagnetic frequencies.
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 tourmausions, or other inclusions.
- Smoky quartz : Black by irradiation (destroyed crystal lattice).
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 metamorc rocks.
- Mossbodarna quartz quarry, Överhogdal, Härjedalen. Massive together with rosy quartz.
- Skellefteå mining district. In granites.
