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A mixture of other minerals, often including pyrite. Lapis lazuli (UK: / ˌlæpɪs ˈlæz (j) ʊli, ˈlæʒʊ -, - ˌli /; US: / ˈlæz (j) əli, ˈlæʒə -, - ˌli /), or lapis for short, is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color.
Amethyst is a purple variety of quartz (SiO. 2) and owes its violet color to irradiation, impurities of iron (Fe3+. ) and in some cases other transition metals, and the presence of other trace elements, which result in complex crystal lattice substitutions. [2][3][4] The irradiation causes the iron Fe3+.
Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined in Bolivia. The colour of the zones visible within ametrine are due to differing oxidation states ...
Fire agate, a variety of chalcedony, is a semi-precious natural gemstone discovered so far only in certain areas of central and northern Mexico and the southwestern United States (New Mexico, Arizona and California). [1] Approximately 24-36 million years ago these areas were subjected to massive volcanic activity during the Tertiary Period.
Charoite (/ tʃæroʊ.aɪt / CHAR-ow-ait) is a rare silicate mineral with the chemical composition K (Ca,Na)2Si4O10(OH,F)•H2O, first described in 1978. It is named after the Chara River, despite its being 70 kilometres (43 mi) away from the discovery place. [ 6 ][ 3 ] When it was discovered, it was thought to be a fake, dyed purple to give it ...
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
Agate (/ ˈ æ ɡ ɪ t / AG-it) is a banded variety of chalcedony, [1] which comes in a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks.The ornamental use of agate was common in Ancient Greece, in assorted jewelry and in the seal stones of Greek warriors, [2] while bead necklaces with pierced and polished agate date back to the 3rd millennium BCE in ...
The OED defines pyrope (from Greek Πυρωπός, lit. "fire-eyed")" as: "In early use applied vaguely to a red or fiery gem, as ruby or carbuncle; (mineralogy) the Bohemian garnet or fire-garnet"; and carbuncle or carbuncle-stone (from Latin "carbunculus", "small glowing ember") as: "A name variously applied to precious stones of a red or ...