Important gemstones

Important gemstones

Important gemstones
mineral gem name colour Mohs hardness* specific gravity*
beryl aquamarine sky blue to greenish blue 7½–8 2.68–2.71
emerald green 2.68–2.74
goshenite colourless; greenish yellow, yellow green, brownish same as aquamarine
heliodor golden yellow same as aquamarine
morganite pink 2.80–2.90
chrysoberyl alexandrite; also cymophane; cat's-eye green in daylight, red in incandescent light 8½ 3.6–3.8
corundum padmaradschah orange 9 4.0–4.1
ruby red
sapphire blue; variable other than red
diamond colourless to faint yellowish tinge; also variable 10 3.52
  feldspar orthoclase pale yellow; flesh red 6 2.6
moonstone colourless; also white to yellowish, and reddish to bluish gray
amazonite (amazon-stone) yellow green to blue green
plagioclase peristerite pastel pink to gray 6–6½ 2.6–2.7
sunstone (aventurine) colourless with reddish glow provided by inclusions
labradorite grayish
almandine carbuncle deep red with a trace of purple 7½ 4.3
andradite demantoid; Uralian emerald deep emerald-green 6½ 3.9
grossularite hessonite; South African jade brownish yellow or orange to orange, red, or green 7¼ 3.6
pyrope dark blood red 7–7½ 3.6
spessartite yellowish orange; brownish to orange red 7¼ 4.2
jadeite Imperial jade pure white to black, red, brown, yellow, blue, mauve, various greens 6 3.2–3.4
nephrite mutton-fat jade deep spinach green to near-white 5–6 3.0–3.4
lazurite lapis; lapis lazuli deep blue, azure blue, greenish blue 5–5½ 2.4–2.95
(bluish coloured with flecks of white and gold) (5½) (2.7–2.9)
olivine peridot; chrysolite yellow green; dark bottle green; olive green 6½–7 3.3–3.5
quartz amethyst purple 7 2.65
cairngorm; smoky quartz smoky gray to brown
citrine yellow
rock crystal colourless
rose quartz pink
agate (moss agate, mocha stone) variable
chalcedony (onyx carnelian, sard, sardonyx, prase, chrysoprase, plasma, bloodstone, heliotrope) variable
jasper variable
cristobalite opal white to colourless; milky to bluish white; variable pale shades 7 2.0–2.3
spinel Balas ruby rubicelle almandine red; also variable 8 3.6
topaz wine yellow; pale blue, green, violet, or red 8 3.5–3.6
tourmaline achroite colourless 7–7½ 3.0–3.2
Brazilian emerald green
dravite brown
indicolite dark blue
rubellite pink
siberite violet
turquoise sky blue; greenish blue 6 2.6–2.8
zircon jargon variable 7½ 4.6–4.7
Matura diamond colourless
hyacinth (jacinth) yellow, orange, red, brown
mineral gem name refractive indices dispersion* transparency crystal system habit remarks
beryl aquamarine epsilon = 1.570–1.580
omega = 1.574–1.586
d = 0.014 transparent hexagonal large, often flawless, crystals with complex terminations
emerald epsilon = 1.571–1.581
omega = 1.577–1.588 simple hexagonal crystals terminated by a flat face; often contains inclusions
goshenite same as aquamarine
heliodor same as aquamarine
morganite epsilon = 1.580–1.590
omega = 1.589–1.601
chrysoberyl alexandrite; also cymophane; cat's-eye alpha = 1.746
beta = 1.748
gamma = 1.756
d = 0.015 transparent orthorhombic flattened crystals often twinned chrysoberyl cat's-eye is chatoyant
corundum padmaradschah epsilon = 1.757–1.768
omega = 1.765–1.776
d = 0.018 transparent hexagonal
ruby flat-terminated crystals fluoresces in ultraviolet light; marked dichroism
sapphire pointed dipyramids marked diochroism
diamond n = 2.4175
d = 0.063 transparent isometric flattened octahedrons; dodecahedrons perfect cleavage parallel to octahedron face; sometimes fluorescent in long-wave ultraviolet light
  feldspar orthoclase alpha = 1.518
beta = 1.522
gamma = 1.522 transparent to opaque monoclinic crystals two excellent cleavages at right angles
moonstone same as orthoclase nodules; masses blue opalecsence; schiller
amazonite (amazon-stone) alpha = 1.514
beta = 1.518
gamma = 1.521 triclinic large crystals variety of microcline
plagioclase peristerite alpha = 1.527–1.577
beta = 1.531–1.585
gamma = 1.538–1.590 transparent to opaque triclinic prismatic crystals iridescent
sunstone (aventurine) spangled appearance
labradorite compact masses brilliantly iridescent over large areas
almandine carbuncle n = 1.830
d = 0.024 transparent (for light-coloured varieties) to opaque isometric euhedral crystals, with dodecahedrons and trapezohedrons most common
andradite demantoid; Uralian emerald n = 1.887
d = 0.057
grossularite hessonite; South African jade n = 1.734
d = 0.028
pyrope n = 1.714
d = 0.027
spessartite n = 1.800
jadeite Imperial jade alpha = 1.640–1.658
beta = 1.645–1.663
gamma = 1.652–1.673 translucent to opaque monoclinic compact or fibrous masses
nephrite mutton-fat jade alpha = 1.600–1.672
beta = 1.614–1.686
gamma = 1.627–1.693 translucent to opaque monoclinic compact or fibrous masses
lazurite lapis; lapis lazuli n = 1.50
(opaque) isometric
(compact masses) lapis lazuli is a rock containing lazurite as its colouring agent; because it is a rock, its composition and properties are variable; properties given in parentheses are for the rock, the others for the mineral lazurite
olivine peridot; chrysolite alpha = 1.635–1.671
beta = 1.652–1.698
gamma = 1.671–1.707
d = 0.020 transparent orthorhombic flattened prismatic crystals; granular masses
quartz amethyst epsilon = 1.553
omega = 1.544
d = 0.013 transparent hexagonal
cairngorm; smoky quartz octahedral crystals
rock crystal
rose quartz
agate (moss agate, mocha stone) translucent to opaque compact masses; nodules
chalcedony (onyx carnelian, sard, sardonyx, prase, chrysoprase, plasma, bloodstone, heliotrope)
cristobalite opal n = 1.435–1.455 opaque tetragonal submicrocrystalline aggregates; globular or kidney-like crusts; irregular concretions contains a variable amount of water, causing the physical properties to vary
spinel Balas ruby rubicelle almandine n = 1.715–1.725
d = 0.020 transparent isometric octahedral crystals; rounded grains; massive fluoresces red in long-wave ultraviolet light
topaz alpha = 1.606–1.629
beta = 1.609–1.631
gamma = 1.616–1.638
d = 0.014 transparent orthorhombic prismatic crystals
tourmaline achroite epsilon = 1.610–1.650
omega = 1.635–1.675
d = 0.016 transparent hexagonal prismatic crystals, often rounded or barrel-shaped; massive
Brazilian emerald
turquoise alpha = 1.61
beta = 1.62
gamma = 1.65 opaque triclinic cryptocrystalline to fine granular massive colour fades on contact with sunlight
zircon jargon epsilon = 1.968–2.015
omega = 1.923–1.960
d = 0.048 transparent tetragonal square prismatic crystals; grains
*Properties given here are for gem-quality material and hence may differ from those of the mineral.
See as table:

* * *

Universalium. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Gemstones —    Burma is renowned for its gemstones, especially pigeon blood rubies, which for centuries have been mined at Mogok (Mogoke) in what is now Mandalay Division. Before the British colonial period, the mining of rubies at Mogok, Sagyin (near… …   Historical Dictionary of Burma (Myanmar)

  • List of important publications in geology — This is an incomplete list, which may never be able to satisfy particular standards for completeness. You can help by expanding it with reliably sourced entries. This is a list of important publications in geology, organized by field. Some… …   Wikipedia

  • gemstone — /jem stohn /, n. a precious or semiprecious stone that can be cut and polished for use as a gem. [bef. 1000; ME gimstone, OE gimstan. See GEM, STONE] * * * Any of various minerals prized for beauty, durability, and rarity. A few noncrystalline… …   Universalium

  • Business and Industry Review — ▪ 1999 Introduction Overview        Annual Average Rates of Growth of Manufacturing Output, 1980 97, Table Pattern of Output, 1994 97, Table Index Numbers of Production, Employment, and Productivity in Manufacturing Industries, Table (For Annual… …   Universalium

  • Diamond — This article is about the mineral. For the gemstone, see Diamond (gemstone). For other uses, including the shape ◊, see Diamond (disambiguation) …   Wikipedia

  • Turquoise — For other uses, see Turquoise (disambiguation). Turquoise Turquoise (tumble finished) one inch (25 mm) long. This pebble is greenish and therefore low grade General …   Wikipedia

  • Diamond simulant — Due to its low cost and close visual likeness to diamond, cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976. The high price of gem grade diamonds, as well as significant ethical concerns of… …   Wikipedia

  • Sri Lanka — Sri Lankan, adj., n. /sree lahng keuh, lang keuh, shree / an island republic in the Indian Ocean, S of India: a member of the Commonwealth of Nations. 18,762,075; 25,332 sq. mi. (65,610 sq. km). Cap.: Colombo. Formerly, Ceylon. Arabic, Serendip.… …   Universalium

  • Ruby — This article is about the mineral. For other uses, see Ruby (disambiguation). Ruby Natural ruby crystals from Winza, Tanzania General Category …   Wikipedia

  • Idar-Oberstein — Schloss Oberstein, castle on the hills above Oberstein …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”