Tridymite in a volcanic rock sample

Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. Polymorphism in Materials science is the ability of a solid material to exist in more than one form or Crystal structure Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in In Crystallography, the triclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three basis vectors Volcanic rock is an Igneous rock of volcanic origin Texture Volcanic rocks are usually fine-grained or Aphanitic to glassy in Its chemical formula is SiO₂. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Tridymite is stable between 870 and 1470 degrees Celsius. It has a Mohs hardness of 6. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 5 to 7, a specific gravity of 2. 28 to 2. 33 and refractive indices of nα=1. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 471 - 1. 482 nβ=1. 472 - 1. 483 nγ=1. 474 - 1. 488. Optically, tridymite has a birefringence of < . 004 and has a 2V between 40 and 90 degrees, it may have wedge, complex or polysynthetic twinning.

Tridymite was first described in 1868 and the type location is in Hidalgo, Mexico. The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. The name is from the Greek Tridymos for triplet as tridymite commonly occurs as twinned crystal trillings. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Crystal twinning occurs when two separate crystals share some of the same Crystal lattice points in a symmetrical manner

See also

• cristobalite
• coesite
• stishovite

References

• Mindat
• Webmineral
• Mineral galleries