Search results
Results From The WOW.Com Content Network
Twinning is crystallographically defined by its twin plane 𝑲 𝟏, the mirror plane in the twin and parent material, and 𝜼 𝟏, which is the twinning shear direction. Deformation twins in Zr are generally lenticular in shape, lengthening in the 𝜼 𝟏 direction and thickening along the 𝑲 𝟏 plane normal.
It occurs with almandine garnet, micas, kyanite; as well as albite, biotite, and sillimanite in gneiss and schist of regional metamorphic rocks. [7] It is the official state mineral of the U.S. state of Georgia and is also to be found in the Lepontine Alps in Switzerland. Staurolite is most commonly found in Fannin County, Georgia. [8]
Garnet and cordierite do not reach complete equilibrium when discovered on the surface, leaving a print of the past P-T environments. The Pressure-Temperature-time path (P-T-t path) is a record of the pressure and temperature (P-T) conditions that a rock experienced in a metamorphic cycle from burial and heating to uplift and exhumation to the ...
Factors influencing habit include: a combination of two or more crystal forms; trace impurities present during growth; crystal twinning and growth conditions (i.e., heat, pressure, space); and specific growth tendencies such as growth striations. Minerals belonging to the same crystal system do not necessarily exhibit the same habit.
It is a type of garnet, distinguished from other garnets in having silicon in octahedral as well as tetrahedral coordination. Majorite was first described in 1970 from the Coorara Meteorite of Western Australia and has been reported from various other meteorites in which majorite is thought to result from an extraterrestrial high pressure shock ...
Some minerals such as garnet form a rhombic dodecahedral crystal habit. As Johannes Kepler noted in his 1611 book on snowflakes ( Strena seu de Nive Sexangula ), honey bees use the geometry of rhombic dodecahedra to form honeycombs from a tessellation of cells each of which is a hexagonal prism capped with half a rhombic dodecahedron.
Omphacite is a member of the clinopyroxene group of silicate minerals with formula: (Ca, Na)(Mg, Fe 2+, Al)Si 2 O 6.It is a variably deep to pale green or nearly colorless variety of clinopyroxene.
Kelyphite is a symplectite formed from the decomposition of garnet. [6] Myrmekite is a globular or bulbous symplectite of quartz in plagioclase. [6] Examples of symplectites formed in Earth materials include dolomite + calcite, [7] aragonite + calcite, [8] and magnetite + clinopyroxene. [9]