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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]
Luminous gemstones. Folktales about luminous gemstones are an almost worldwide motif in mythology and history among Asian, European, African, and American cultures. Some stories about light-emitting gems may have been based on luminescent and phosphorescent minerals such as diamonds.
Gemstones of the World revised 5th edition, 2013 by Walter Schumann ISBN 978-1454909538 Smithsonian Handbook: Gemstones by Cally Hall, 2nd ed. 2002 ISBN 978-0789489852 v
Phosphosiderite is often found in a bright orchid-purple tint with yellow-colored streaks. The vein-like streaks found in the stone are known as cacoxenite. Four other rare color variants are rose red, brown-reddish yellow, mossy green, and dark shades of purple. Phosphosiderite can also be found as a colorless mineral.
White phosphorus (left), red phosphorus (center left and center right), and violet phosphorus (right) White phosphorus and resulting allotropes. Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and ...
Purpurite is a manganese phosphate mineral with the formula MnPO 4, with varying amounts of iron depending upon its source. It occurs in color ranges from brownish black via purple and violet to dark red. [3] Purpurite forms a series with the iron-bearing endmember heterosite, FePO 4. [4]
Howlite was discovered near Windsor, Nova Scotia, in 1868 by Henry How (1828–1879), a Canadian chemist, geologist, and mineralogist. [6] [7] How was alerted to the unknown mineral by miners in a gypsum quarry, who found it to be a nuisance. He called the new mineral silico-boro-calcite; it was given the name howlite by the American geologist ...
Typically quartz and feldspar; lithic fragments are also common. Other minerals may be found in particularly mature sandstone. Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks.