McClure, Tess (17 September 2019). "Dark crystals: the brutal reality behind a booming wellness craze". The Guardian. ISSN 0261-3077 . Retrieved 25 September 2019. The ancient Greeks believed amethyst gems could prevent intoxication, [23] while medieval European soldiers wore amethyst amulets as protection in battle in the belief that amethysts heal people and keep them cool-headed. [24] Beads of amethyst were found in Anglo-Saxon graves in England. [25] Anglican bishops wear an episcopal ring often set with an amethyst, an allusion to the description of the Apostles as "not drunk" at Pentecost in Acts 2:15. [26] The largest documented single crystal of quartz was found near Itapore, Goiaz, Brazil; it measured approximately 6.1m × 1.5m × 1.5m and weighed 39,916 kilograms. [81] Mining [ edit ] There are many different varieties of quartz, several of which are classified as gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. The color of amethyst has been demonstrated to result from substitution by irradiation of trivalent iron (Fe 3+) for silicon in the structure, [4] [12] in the presence of trace elements of large ionic radius, [3] and to a certain extent, the amethyst color can naturally result from displacement of transition elements even if the iron concentration is low. Natural amethyst is dichroic in reddish violet and bluish violet, [4] but when heated, turns yellow-orange, yellow-brown, or dark brownish and may resemble citrine, [13] but loses its dichroism, unlike genuine citrine. When partially heated, amethyst can result in ametrine.

The word "quartz" comes from the German Quarz ⓘ, [11] which is of Slavic origin (Czech miners called it křemen). Other sources attribute the word's origin to the Saxon word Querkluftertz, meaning cross-vein ore. [12] [13] Pliny says about amethysts: "The falsehoods of the magicians would persuade us that these stones are preventive of inebriety, and that it is from this that they have derived their name." See Chapter 40 of Book 37 of Pliny the Elder's The Natural History.

THE GEMSTONE BOOK Gemstones, Organic Substances & Artificial Products — Terminology & Classification (PDF). The World Jewellery Confideration (CIBJO). 2012. Archived from the original (PDF) on August 12, 2012 . Retrieved June 27, 2012. Webster, Richard (8 September 2012). "Citrine". The Encyclopedia of Superstitions. p.59. ISBN 9780738725611. Easily diagnosed from the very strong pleochrosim with the secondary colour being the orange-yellow. A pleasing inclusion to find. Quartz Inclusions: Pyrite

The Quartz Watch– Walter Guyton Cady". The Lemelson Center, National Museum of American History, Smithsonian Institution. Archived from the original on 4 January 2009. All the while, the stone’s healing energy can fill the room. Some say that its potent vibrational energy is so strong that you can feel it wash over you whenever you enter the room it’s in. Magnesium Aluminium Phosphate (MgAl2(PO4)2(OH)2) blue, bright blue, greenish-blue to bluish-white in colour. Forms in the monoclinic crystal system and has a prismatic habit, sometimes with pyramidal terminations and usually short, stout crystals. One of the less common inclusions in quartz. Quartz Inclusions: Piemontite The various healing properties that Blue Quartz has are quite profound. Like its more common Quartz cousins, this crystal is potent enough to influence several aspects of your life. From your day-to-day habits to your grander life journey, Blue Quartz can impact it all! Michael O'Donoghue (1997). Synthetic, Imitation, and Treated Gemstones. Taylor & Francis. pp.124–125. ISBN 978-0-7506-3173-0.Amethyst Jewelry and Gemstones Information - International Gem Society IGS". gemsociety.org . Retrieved October 3, 2014. Blue Quartz". Mindat.org. Archived from the original on 24 February 2017 . Retrieved 24 February 2017. Cristobalite has no gem significance but appears in some types of volcanic glass as white globules and crystals resembling snowflakes. These form as a result of rapid cooling from high temperature. Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10]