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 number of circuits for consumer electronics products such as computers, cell phones, 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 tourmaline inclusions, 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.
• 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.
• 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.
• Långban, Värmland. Massive.