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Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH −, F − and Cl − ion, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca 10 ( PO 4) 6 (OH,F,Cl) 2, and the crystal unit cell formulae of the individual ...
Amethyst. Amethyst is a violet variety of quartz. The name comes from the Koine Greek αμέθυστος amethystos from α- a-, "not" and μεθύσκω ( Ancient Greek) methysko / μεθώ metho ( Modern Greek ), "intoxicate", a reference to the belief that the stone protected its owner from drunkenness. [ 1]
The mineral or gemstonechrysoberylis an aluminateof berylliumwith the formula BeAl2O4. [5][6]The name chrysoberyl is derived from the Greekwords χρυσός chrysosand βήρυλλος beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and berylare two completely different gemstones, although they both ...
This is a list of minerals which have Wikipedia articles. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species. Within a mineral species there may be variation in physical properties or minor amounts of impurities that are recognized by ...
Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF 2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 4 as fluorite.
Ochre is a family of earth pigments, which includes yellow ochre, red ochre, purple ochre, sienna, and umber. The major ingredient of all the ochres is iron (III) oxide-hydroxide, known as limonite, which gives them a yellow colour. A range of other minerals may also be included in the mixture: [ 5]: 134. Yellow ochre ( Goldochre) pigment.
Pyrrhotite ( pyrrhos in Greek meaning "flame-coloured") is an iron sulfide mineral with the formula Fe (1-x) S (x = 0 to 0.125). It is a nonstoichiometric variant of FeS, the mineral known as troilite . Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is weakly magnetic.
Scale box in millimeters. Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all types of igneous rocks can display some degree of porphyritic texture.