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Encyclopedia > Amethyst
Amethyst

General
Category Mineral variety
Chemical formula Silica (silicon dioxide, SiO2)
Identification
Color purple
Crystal habit 6-sided prism ending in 6-sided pyramid (typical)
Crystal system rhombohedral class 32
Twinning Dauphine law, Brazil law, and Japan law
Cleavage None
Fracture Conchoidal
Mohs Scale hardness 7–lower in impure varieties
Luster Vitreous/glossy
Refractive index nω = 1.543–1.553 nε = 1.552–1.554
Optical Properties Uniaxial (+) (Positive)
Birefringence +0.009 (B-G interval)
Pleochroism None
Streak White
Specific gravity 2.65 constant; variable in impure varieties
Melting point 1650±75 °C
Solubility H2O insoluble
Diaphaneity Transparent to translucent
Other Characteristics Piezoelectric

Amethyst is a purple variety of quartz often used as an ornamental stone in jewellery. The name comes from the Ancient Greek a- ("not") and methustos ("intoxicated"), a reference to the belief that the stone protected its owner from drunkenness; the ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief that it would prevent intoxication. Amethyst may refer to: Amethyst, a semi-precious mineral. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (2272 × 1704 pixel, file size: 825 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... In crystallography, the rhombohedral (or trigonal) crystal system is one of the 7 lattice point groups. ... It has been suggested that twin boundary be merged into this article or section. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For other uses, see Fracture (disambiguation). ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals or boron... Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... The melting point of a solid is the temperature range at which it changes state from solid to liquid. ... Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... For other uses, see Quartz (disambiguation). ... An ornamental stone is a stone used as a decoration. ... For the Korean music group, see Jewelry (group). ... Beginning of Homers Odyssey The Ancient Greek language is the historical stage of the Greek language[1] as it existed during the Archaic (9th–6th centuries BC) and Classical (5th–4th centuries BC) periods in Ancient Greece. ... The Drunkenness of Noah by Giovanni Bellini Drunkenness is the state of being intoxicated by consumption of alcohol to a degree that mental and physical facilities are noticeably impaired. ... The term ancient Greece refers to the periods of Greek history in Classical Antiquity, lasting ca. ... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ... ...

Contents

Chemistry

Amethyst is the purple variety of quartz, its chemical formula is SiO2. For other uses, see Quartz (disambiguation). ...


In the 20th century, the color of amethyst was attributed to the presence of manganese. However, since it is capable of being greatly altered and even discharged by heat, the color was believed by some authorities to be from an organic source. Ferric thiocyanate was suggested, and sulfur was said to have been detected in the mineral. General Name, symbol, number manganese, Mn, 25 Chemical series transition metals Group, period, block 7, 4, d Appearance silvery metallic Standard atomic weight 54. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... The structure and bonding of the thiocyanate ion Thiocyanate (also known as sulphocyanate or thiocyanide) is the anion, [SCN]−. Common compounds include the colourless salts potassium thiocyanate and sodium thiocyanate. ... This article is about the chemical element. ...


More recent work has shown that amethyst's coloration is due to ferric iron impurities.[1] Further study has shown a complex interplay of iron and aluminium is responsible for the color.[2] General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... Aluminum redirects here. ...


On exposure to heat, amethyst generally becomes yellow, and much of the citrine, cairngorm, or yellow quartz of jewelry is said to be merely "burnt amethyst". Veins of amethystine quartz are apt to lose their color on the exposed outcrop[citation needed]. This article is about the color. ... Citrine Citrine, also called citrine quartz is an amber-colored gemstone. ... Cairngorm is a variety of quartz crystal found in the Cairngorm Mountains of Scotland. ...


Synthetic amethyst is made to imitate the best quality amethyst. Its chemical and physical properties are so similar to that of natural amethyst that it cannot be differentiated with absolute certainty without advanced gemological testing (which is often cost-prohibitive). There is one test (which is not 100 percent certain) based on "Brazil law twinning" (a form of quartz twinning where right and left hand quartz structures are combined in a single crystal[3] which can be used to identify synthetic amethyst rather easily. In theory however it is possible to create this material synthetically as well, but this type is not available in large quantities in the market.[4] It has been suggested that twin boundary be merged into this article or section. ...


Composition

Amethyst is composed of an irregular superposition of alternate lamellae of right-handed and left-handed quartz. It has been shown that this structure may be due to mechanical stresses. Lamellar structures or microstructures are composed of fine, alternating layers of different materials in the form of lamellae. ...


Because it has a hardness of seven on the Mohs scale, amethyst is suitable for use in jewelry. Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ...

A polished amethyst gem stone.
A polished amethyst gem stone.

Image File history File linksMetadata Amethystvb. ... Image File history File linksMetadata Amethystvb. ...

Hue and tone

Amethyst occurs in primary hues from a light slightly-pinkish violet to a deep grape purple. Amethyst may exhibit one or both secondary hues, red and/or blue. The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75–80 percent, 15–20 percent blue and (depending on the light source) red secondary hues.[4]


History

Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglios. Beads of amethyst were found in Anglo-Saxon graves in England. It is a widely distributed mineral, but fine, clear specimens that are suitable for cutting as ornamental stones are confined to few localities. Such crystals occur either in the cavities of mineral-veins and in granitic rocks, or as a lining in agate geodes. A huge geode, or "amethyst-grotto", from near Santa Cruz in southern Brazil was exhibited at the Düsseldorf, Germany Exhibition of 1902. For other uses, see Gemstone (disambiguation). ... Intaglio in jewellery, refers to incised (negative) image-making, and is the opposite of cameo. ... For other uses, see Anglo-Saxon. ... For other uses, see England (disambiguation). ... For other uses, see Mineral (disambiguation). ... For other uses, see Crystal (disambiguation). ... For other uses, see granite (disambiguation). ... For other uses, see Agate (disambiguation). ... Geode, halved and polished Geode, halved and polished Geodes (Greek geoides, earthlike) are geological rock formations which occur in sedimentary and certain volcanic rocks. ... Düsseldorf - Wikipedia /**/ @import /skins-1. ... Year 1902 (MCMII) was a common year starting on Wednesday (link will display calendar) of the Gregorian calendar (or a common year starting on Tuesday [1] of the 13-day-slower Julian calendar). ...


Alternate terminology

Several descriptive terms have been coined in the gem trade to describe the colors of amethyst. "Rose de France" is usually a pale pinkish lavender or lilac shade (usually the least-sought color). The most prized color is an intense violet with red flashes and is called "Siberian", although gems of this color may occur from several locations other than Siberia, notably Uruguay and Zambia. In more recent times, certain gems (usually of Bolivian origin) that have shown alternate bands of amethyst purple with citrine orange have been given the name ametrine. This article is about Siberia as a whole. ... Ametrine Ametrine (or trystine) is a naturally occurring variety of quartz. ...


Purple corundum, or sapphire of amethystine tint, is called Oriental amethyst, but this expression is often applied by jewelers to fine examples of the ordinary amethystine quartz, even when not derived from eastern sources. Professional gemological associations, such as the Gemological Institute of America (GIA) or the American Gemological Society (AGS), discourage the use of the term "Oriental amethyst" to describe any gem, as it may be misleading. Corundum (from Tamil kurundam) is a crystalline form of aluminium oxide and one of the rock-forming minerals. ... For other uses, see Sapphire (disambiguation). ... The Gemological Institute of America, or GIA, is a non-profit institute dedicated to research and education in the field of gemology. ... The American Gem Society (AGS) is a trade association of professional gemologists founded in 1934 by Robert M. Shipley, who also founded the Gemological Institute of America (GIA). ...


The Second Book of Pseudo-Albertus Magnus, Of the Vertues of Certaine Stones, refers to amethysts by the name Amarictus.

Six carat (1.2 g) pear-shape amethyst ring

Image File history File links Srr046a. ... Image File history File links Srr046a. ...

Geographic distribution

Amethyst is produced in abundance from the state of Minas Gerais in Brazil where it occurs in large geodes within volcanic rocks. It is also found and mined in South Korea. The largest opencast amethyst vein in the world is in Maissau, Lower Austria. Many of the hollow agates of Brazil and Uruguay contain a crop of amethyst crystals in the interior. Much fine amethyst comes from Russia, especially from near Mursinka in the Ekaterinburg district, where it occurs in drusy cavities in granitic rocks. Many localities in India yield amethyst. Capital (and largest city) Belo Horizonte Demonym Mineiro Government  -  Governor Aécio Neves  -  Vice Governor Antônio Augusto Junho Anastasia Area  -  Total 588,528. ... Geode, halved and polished Geode, halved and polished Geodes (Greek geoides, earthlike) are geological rock formations which occur in sedimentary and certain volcanic rocks. ... Ignimbrite is a deposit of a pyroclastic flow. ... Photograph of snow-covered Yekaterinburg Yekaterinburgs Church on the Blood, built on the spot where the Tsar and his family were murdered. ...

Museum-quality piece of Amethyst
Museum-quality piece of Amethyst

. One of the largest global amethyst producers is Zambia with an annual production of about 1,000 t. Image File history File linksMetadata Download high-resolution version (3008x2000, 3512 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Amethyst Metadata This file contains additional information, probably added from the digital camera or scanner used to create... Image File history File linksMetadata Download high-resolution version (3008x2000, 3512 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Amethyst Metadata This file contains additional information, probably added from the digital camera or scanner used to create...


Amethyst occurs at many localities in the United States, but these specimens are rarely fine enough for use in jewelry. Among these may be mentioned Amethyst Mountain, Texas; Yellowstone National Park; Delaware County, Pennsylvania; Haywood County, North Carolina; Deer Hill and Stow, Maine. It is found also in the Lake Superior region. Amethyst is relatively common in Ontario, and in various locations throughout Nova Scotia, but uncommon elsewhere in Canada. For other uses, see Texas (disambiguation). ... Yellowstone redirects here. ... Delaware County (also known colloquially as Delco) is a county located in the U.S. state of Pennsylvania. ... Haywood County is a county located in the U.S. state of North Carolina. ... Official language(s) None (English and French de facto) Capital Augusta Largest city Portland Area  Ranked 39th  - Total 33,414 sq mi (86,542 km²)  - Width 210 miles (338 km)  - Length 320 miles (515 km)  - % water 13. ... For the the Quebec municipality, see Lac-Supérieur. ... This article is about the Canadian province. ... Motto: Munit Haec et Altera Vincit (Latin: One defends and the other conquers) Capital Halifax Largest city Halifax Regional Municipality Official languages English (de facto) Government Lieutenant-Governor Mayann E. Francis Premier Rodney MacDonald (PC) Federal representation in Canadian Parliament House seats 11 Senate seats 10 Confederation July 1, 1867...


Value

Traditionally included in the cardinal, or most valuable, gemstones (along with diamond, sapphire, ruby, and emerald), amethyst has lost much of its value due to the discovery of extensive deposits in locations such as Brazil. The highest grade amethyst (called "Deep Russian") is exceptionally rare and therefore its value is dependent on the demand of collectors when one is found. It is however still orders of magnitude lower than the highest grade sapphires or rubies (Padparadscha sapphire or "pigeon's blood" ruby).[4] This article is about the mineral. ... For other uses, see Sapphire (disambiguation). ... This article is about the mineral. ... This article or section does not cite its references or sources. ... There are very few or no other articles that link to this one. ...


Amethyst in folklore and astrology

Amethyst is the birthstone associated with February. It is also associated with the astrological signs of Pisces, Aries (especially the violet and purple variety), Aquarius, and Sagittarius. It is a symbol of heavenly understanding, and of the pioneer in thought and action on the philosophical, religious, spiritual, and material planes. Ranking members of the Roman Catholic Church traditionally wear rings set with a large amethyst as part of their office. A birthstone is a gemstone or other semi-precious stone which is associated with a month of the Gregorian Calendar. ... Astrological represent twelve equal segments or divisions of the zodiac. ... Symbol of Pisces Pisces is an Astrological sign, which originated from the constellation Pisces, and is the twelfth sign of the zodiac. ... Aries, the ram, is the first astrological sign of the zodiac and its origins are from the Aries constellation. ... Spirit of Aquarius Aquarius is the eleventh astrological sign in the Zodiac, originating from the constellation Aquarius. ... Sagittarius the archer Sagittarius is the ninth astrological sign in the Zodiac, originating from the constellation of Sagittarius. ... The Roman Catholic Church, most often spoken of simply as the Catholic Church, is the largest Christian church, with over one billion members. ...


The Greek word "amethystos" (αμέθυστος) basically can be translated as "not drunken". Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were often carved from it. Supposedly, when a drunken Dionysus was pursuing a maiden called Amethystos, who refused his affections, she prayed to the gods to remain chaste. The goddess Artemis granted the prayer, transforming her into a white stone; humbled by Amethystos' desire to remain chaste, Dionysus poured wine over the stone she had become as an offering, dyeing the crystals purple. This article is about the ancient deity. ... For other uses, see Artemis (disambiguation). ...


Variants of the story include that Dionysus, the god of intoxication, had been insulted by a mortal and swore revenge on the next mortal who crossed his path, creating fierce tigers to carry out his wish; the mortal turned out to be a beautiful young woman, Amethystos, who was on her way to pay tribute to Artemis. Her life is spared by Artemis, who transforms the maiden into a statue of pure crystalline quartz to protect her from the brutal claws. Dionysus wept tears of wine in remorse for his action at the sight of the beautiful statue. The god's tears stained the quartz purple.[5] Another variation involves the goddess Rhea presenting Dionysus with the amethyst stone to preserve the winedrinker's sanity.[6] Rhea (or Ria meaning she who flows) was the Titaness daughter of Uranus and of Gaia. ...


See also

Wikimedia Commons has media related to:

Gem animals. ...

Notes

  1. ^ Klein, Cornelis and Hurlbut, Cornelius S., 1985 Manual of Mineralogy (after JD Dana) 20th edition, p. 441, John Wiley & Sons, New York
  2. ^ Cohen, Alvin J., 1985, Amethyst color in quartz,the result of radiation protection involving iron', American Mineralogist, V. 70, pp 1180-1185
  3. ^ Quartz Page Twinning Crystals. Retrieved on 2007-05-28.
  4. ^ a b c Secrets of the Gem Trade; The Connoisseur's Guide to Precious Gemstones Richard W Wise, Brunswick House Press, Lenox, Massachutes., 2003
  5. ^ source
  6. ^ (Nonnus, Dionysiaca, XII.380)

Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 148th day of the year (149th in leap years) in the Gregorian calendar. ...

References

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. Encyclopædia Britannica, the eleventh edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...

  • Amethyst. part of a poster by the Juneau – John Rishel Mineral Information Center. Alaska office of the United States Bureau of Land Management. Retrieved on 2006-09-11.
  • Ure, Andrew (1827). A Dictionary of Chemistry. Printed for Thomas Tegg, (et al.), 141. Retrieved on 2006-09-11. “The amethyst is a gem of a violet colour, and great brilliancy, said to be as hard as the ruby or sapphire, from which it only differs in colour. This is called the oriental amethyst, and is very rare. When it inclines to the purple or rosy colour, it is more esteemed than when it is nearer to the blue. These amethysts have the same figure, hardness, specific gravity, and other qualities, as the best sapphires or rubies, and come from the same places, particularly from Persia, Arabia, Armenia and the West Indies. The occidental amethysts are merely coloured crystal or quartz.” 
  • http://mineral.galleries.com/minerals/gemstone/amethyst/amethyst.htm
  • http://mindat.org/min-198.html
  • http://gemstone.org/gem-by-gem/english/amethyst.html
Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 254th day of the year (255th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 254th day of the year (255th in leap years) in the Gregorian calendar. ... For the Korean music group, see Jewelry (group). ... For the CSI episode of the same name, see Precious Metal (CSI episode). ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... For other uses, see Palladium (disambiguation). ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... General Name, Symbol, Number rhodium, Rh, 45 Chemical series transition metals Group, Period, Block 9, 5, d Appearance silvery white metallic Standard atomic weight 102. ... This article is about the chemical element. ... An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... Electrum coin of the Byzantine Emperor Alexius I Comnenus. ... Rose gold is a gold and copper alloy widely used for specialized jewelry due to its reddish color. ... Sterling silver is an alloy of silver containing 92. ... White gold is an alloy of gold and at least one white metal, such as silver or palladium. ... In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid (HCl) to form hydrogen. ... Brazen redirects here. ... This article is about the metal alloy. ... For other uses, see Copper (disambiguation). ... The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch defines St. ... For other uses, see Gemstone (disambiguation). ... Aventurine is used for a number of applications, including landscape stone, building stone, aquaria, monuments, and jewelry. ... For other uses, see Agate (disambiguation). ... The mineral or gemstone chrysoberyl, not to be confused with beryl, is an aluminate of beryllium with the formula BeAl2O4. ... This article is about the mineral. ... Imprint of a carnelian seal with Brahmi inscription Kusumadasasya (Flowers servant). 4-5th century CE, probably Punjab. ... Citrine Citrine, also called citrine quartz is an amber-colored gemstone. ... This article is about the mineral. ... This article or section does not cite its references or sources. ... Garnet is a group of minerals that have been used since the Bronze Age as gemstones and abrasives. ... A selection of antique, hand-crafted Chinese jade (jadeite) buttons Unworked Jade Jade is used as an ornamental stone, the term jade is applied to two different rocks that are made up of different silicate minerals. ... Polished jasper pebble, one inch (2. ... For other uses, see Malachite (disambiguation). ... Lapis lazuli, also known as just lapis, is one of the stones with the longest tradition of being considered a gem, with a history stretching back to 5000 BC. Deep blue in color and opaque, this gemstone was highly prized by the pharaohs of ancient Egypt, as can be seen... Moonstone is typically a potassium aluminium silicate, with the chemical formula KAlSi3O8 [1] The most common moonstone is of the mineral Adularia. ... This article is about the mineral. ... For other uses, see Opal (disambiguation). ... This article is about the mineral. ... For other uses, see Quartz (disambiguation). ... This article is about the mineral. ... For other uses, see Sapphire (disambiguation). ... Sodalite is a rare, rich royal blue mineral widely enjoyed as an ornamental stone. ... Sunstone, a feldspar exhibiting in certain directions a brilliant spangled appearance, which has led to its use as an ornamental stone. ... Tanzanite is the blue/purple variety of the mineral zoisite discovered in the Meralani Hills of northern Tanzania in 1967, near the city of Arusha. ... Polished tigers eye gemstone Tigers eye (also Tigers eye, Tiger eye) is a chatoyant gemstone that is usually yellow- to red-brown, with a silky luster. ... This article is about the mineral or gemstone. ... For other uses, see Gemstone (disambiguation). ... For other uses, see Amber (disambiguation). ... Copal is a type of resin, sometimes referred to as pom (the Maya language name). ... Extant Subclasses and Orders Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea [1][2]  See Anthozoa for details For other uses, see Coral (disambiguation). ... A sample of jet Jet is a geological material that is not considered a mineral in the true sense of the word, but rather, a mineraloid derived from decaying wood under extreme pressure, thus organic in origin. ... For other uses, see Pearl (disambiguation). ... R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... For other uses, see Mineral (disambiguation). ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Coesite is a form of silicon dioxide that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) are applied to quartz. ... Common in volcanic rocks, cristobalite is a high-temperature polymorph of quartz and tridymite. ... Moganite is a silicate mineral with the chemical formula SiO2 (silicon dioxide) that was discovered in 1984. ... For other uses, see Quartz (disambiguation). ... Stishovite is a form of silicon dioxide that is formed at very high pressure (~ 100 kbar) and temperature (> 1200 ° C), so far as is known only in meteorite impact craters and their ejecta. ... Tridymite Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. ... Cryptocrystalline is a rock texture which is so finely crystalline, that is, made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. ... Chalcedony knife, AD 1000-1200 Bloodstone redirects here. ... Chert Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ... This article is about the sedimentary rock. ... Polished jasper pebble, one inch (2. ... Wax and paraffin are amorphous. ... fulgurite Fulgurites (from the Latin fulgur meaning thunderbolt) are natural hollow carrot-shaped glass tubes formed in quartzose sand or soil by lightning strikes. ... Lechatelierite is silica glass, amorphous SiO2. ... For other uses, see Opal (disambiguation). ... Quartzite Quartzite (from German Quarzit[1]) is a hard, metamorphic rock which was originally sandstone. ... Polished tigers eye gemstone Tigers eye (also Tigers eye, Tiger eye) is a chatoyant gemstone that is usually yellow- to red-brown, with a silky luster. ... Chalcedony knife, AD 1000-1200 Bloodstone redirects here. ... For other uses, see Agate (disambiguation). ... Imprint of a carnelian seal with Brahmi inscription Kusumadasasya (Flowers servant). 4-5th century CE, probably Punjab. ... Chrysoprase Chrysoprase or chrysophrase is a gemstone variety of chalcedony (fibrous form of quartz) that contains small quantities of nickel. ... A Mexican agate, showing only a single eye, has received the name of cyclops. ... Heliotrope is another term for bloodstone, a form of Chalcedony. ... Moss agate pebble, 1 inch (25 mm) long. ... Wikipedia does not have an article with this exact name. ... This article is about the mineral. ... Sard is a reddish-brown chalcedony, SiO2, much used by the ancients as a gemstone. ... Polished jasper pebble, one inch (2. ... Chert Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ... Bruneau Jasper is a gemstone that comes from the region near the Bruneau River in western Idaho, United States. ... Mozarkite is a form of chert (flint). ... For other uses, see Opal (disambiguation). ... Geyserite is a form of opaline silica that is often found around hot springs and geysers. ... Menilite is a reddish-brown form of opal, also known as liver opal or leberopal. ... For other uses, see Quartz (disambiguation). ... Ametrine Ametrine (or trystine) is a naturally occurring variety of quartz. ... Cairngorm is a variety of quartz crystal found in the Cairngorm Mountains of Scotland. ... Citrine Citrine, also called citrine quartz is an amber-colored gemstone. ... Herkimer diamonds from Fulton County, NY. Herkimer diamond is the misnomerous name for double-terminated quartz first discovered in exposed outcrops of dolostone at Little Falls in Herkimer County, New York and the Mohawk River Valley. ... Milk quartz rock Milk quartz or Milky quartz is probably the most common variety of quartz and can be found almost anywhere. ... An elephant carved in rose quartz, 4 inches (10 cm) long Rose quartz is a type of quartz which exhibits a pale pink to rose red hue. ... Categories: Mineral stubs | Minerals | Quartz varieties ... Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. ...

  Results from FactBites:
 
Amethyst - Wikipedia, the free encyclopedia (824 words)
In the 20th century, the color of amethyst was attributed to the presence of manganese.
Amethyst is composed of an irregular superposition of alternate lamellae of right-handed and left-handed quartz.
Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglios.
HMS Amethyst (U16) - Wikipedia, the free encyclopedia (889 words)
At 08:30 on April 20 Amethyst was attacked by artillery of the PLA.
On July 30, 1949 Amethyst slipped her chain and headed downriver in the dark, beginning a 104-mile dash for freedom running the gauntlet of Communist guns on both banks of the river.
Amethyst re-enacted her role in the 1957 film Yangtse Incident: The Story of HMS Amethyst (released as Battle Hell in the US, and also as Escape of the Amethyst and Their Greatest Glory) starring Richard Todd as Kerans.
  More results at FactBites »

 
 

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