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QAPF diagram for classification of plutonic rocks. A QAPF diagram is a doubled-triangle plot diagram used to classify intrusive igneous rocks based on their mineralogy.The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)", which are the four mineral groups used for classification in a QAPF diagram.
Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. [6] The color of smoky quartz is produced when natural radiation, emitted from the surrounding rock, activates color centers around aluminum impurities within the ...
Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...
Smoky quartz with spessartine on top of feldspar matrix, featuring different crystal habits (shapes). In mineralogy, crystal habit is the characteristic external shape of an individual crystal or aggregate of crystals.
Michel-Lévy interference colour chart issued by Zeiss Microscopy. In optical mineralogy, an interference colour chart, also known as the Michel-Levy chart, is a tool first developed by Auguste Michel-Lévy to identify minerals in thin section using a petrographic microscope.
Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
High quality quartz crystals are single-crystal silica with optical or electronic properties that make them suitable for hardstone carvings. The Hindu temples in South India use this semi-precious mineral for making Shiva Lingams. Sphatikam beads are made from translucent rose quartz are cut and polished as beads.
Thermoluminescence from heating chlorophane specimens on a hotplate. Triboluminescence from rubbing together two quartz crystals.. First, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light, friction, or heat.