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Kyanite

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Kyanite is commonly found in aluminum-rich metamorphic pegmatites and / or sedimentary rocks and is commonly a blue silicate mineral. Cyanide in metamorphic rocks show better pressures than four kilobars. Although it is undoubtedly strong at stress and low temperature, it is generally sufficiently high under these conditions where water hobbyist, muscovite, pyrophyllite or kaolinite-containing aqueous aluminosilicates are replaced. Kyanite is also called disten, ranetite and cyanide.

Name: From the Greek for blue, in allusion to its common dark blue color.

Type Material: Mining Academy, Freiberg, Germany, 22491.

Association: Staurolite, andalusite, sillimanite, talc, \hornblende,” gedrite, mullite, corundum.

Occurrence of Kyanite

Kyanite takes place in gneiss, schist, pegmatite, and quartz veins attributable to high pressure regional metamorphism of mainly pelitic rocks.[citation needed] It takes place as detrital grains in sedimentary rocks.[citation needed] It takes place related to staurolite, andalusite, sillimanite, talc, hornblende, gedrite, mullite and corundum.

Physical Properties of Kyanite

Chemical ClassificationSilicate
ColorBlue, white, gray, green, colorless
StreakWhite, colorless
LusterVitreous, pearly
DiaphaneityTransparent to translucent
CleavagePerfect in two directions, faces sometimes striated
Mohs HardnessKyanite often occurs in long, bladed crystals. These have a hardness of 4.5 to 5 along the length of the crystals and 6.5 to 7 across the width of the crystals.
Specific Gravity3.5 to 3.7
Diagnostic PropertiesColor, cleavage, bladed crystals
Chemical CompositionAl2SiO5
Crystal SystemTriclinic
UsesCeramics, gemstones

Optical Properties of Kyanite

Two kyanite porphyroblasts, within a pelite from the Grenville Province, showing euhedral shapes and the presence of cleavage, evident in the lower grain.
The kyanite porphyroblasts have inclusions of quartz and the muscovite fabric is evident between the lower grain and the bottom of the image.
Property
Value
FormulaAl2SiO5
Crystal SystemTriclinic
Crystal HabitElongate or columnar crystals in bladed aggregates
CleavagePerfect cleavage on (100) and good cleavage on (010) intersect at 79°
Color/PleochroismPale blue in hand samples.  Colorless to light patchy blue in thin section.  Weak pleochroism in thin section where X= colorless, Y= light violet blue, and Z= light cobalt blue
Optic SignBiaxial (-)
2V78°-84°
Optic OrientationZ: inclined 27° – 32° to the c axis
Y: inclined 27° – 32° to the b axis
X: inclined a few degrees to the a axis
Refractive Indices
alpha =
beta =
gamma =
delta =
1.710-1.718
1.719-1.725
1.724-1.734
0.012-0.016
ElongationPrismatic crystals and cleavage fragments are length slow
ExtinctionInclined (see optic orientation).
DispersionWeak r > v
Distinguishing FeaturesColorless and dark in thin section with high positive relief! Second-order interference colors. Two prominent, high angle cleavages occur parallel and perpendicular to the length of the crystal blades. Hardness = 4-5 parallel to c and 7.5 at right angles to c. G = 3.53 to 3.67. Streak is white. Luster is vitreous.
ReferencesNesse, William D. (2000) Introduction to mineralogy. New York: Oxford University Press.
Nesse, William D. (1986) Introduction to optical mineralogy. New York: Oxford University Press.
EditorsWendy Kelly (’05), Rhiannon Nolan (’19)

Uses of Kyanite

  • Kyanite is used to fabricate a wide variety of products. An important use is inside the manufacture of refractory products inclusive of the bricks, mortars, and kiln furnishings used in excessive-temperature furnaces. For foundries, the molds that are used for casting excessive-temperature metals are regularly made with kyanite.
  • Kyanite is likewise in products used inside the automotive and railroad industries in which heat resistance is vital. Mullite, a shape of calcined kyanite, is used to make brake footwear and take hold of facings.
  • Kyanite has homes that make it pretty nicely applicable for the manufacture of a excessive-refractory-strength porcelain – a porcelain that holds its energy at very excessive temperatures. A familiar use of this form of porcelain is the white porcelain insulator on a spark plug.
  • Kyanite is also utilized in some of the extra common forms of porcelain, including those used to make dentures, sinks, and bathroom furnishings.
  • Kyanite’s heat resistance and hardness make it an super fabric to be used within the manufacture of grinding wheels and slicing wheels. It isn’t used as the primary abrasive; rather, it is used as part of the binding agent that holds the abrasive debris collectively within the shape of a wheel.
  • Kyanite, in contrast to most other minerals, can extend extensively whilst heated. Depending upon particle size, temperatures, and heating situations, kyanite can make bigger to as much as two times its original volume while heated. This growth is predictable. In the manufacture of certain refractory products, unique quantities of kyanite are added to the uncooked material (which shrinks at some stage in heating) to preserve extent within the completed product.
  • Kyanite is a gemstone that you will not often come upon within the standard jewelry shop. Most human beings have no longer heard of kyanite, as it’s far occasionally used in earrings. It is an “amazing” gem. Perhaps that is what makes it so thrilling?

Distribution of Kyanite

Widely distributed, even in good crystals.

  • From Mt. Greiner, Zillertal, Tirol, Austria. At Alpe Sponda, Pizzo Forno, and at Alpe Campolungo, Tessin, Switzerland.
  • In the Ptschtal, Trentino-Alto Adige, Italy.
  • From Roros, Norway. Around Yekaterinburg (Sverdlovsk), Ural Mountains, Russia.
  • At Elovyi, Klavoloke, Karelia.
  • From Sultan Hamud, Machakos district, Kenya.
  • Large crystals from a number of localities in Minas Gerais, In the USA, at Lyme, Grafton Co., New Hampshire; at Judd’s Bridge, Litcheld Co., Connecticut; at Darby, Delaware Co., Pennsylvania; from near Bakersville, Mitchell Co., and near Burnsville, Yancy Co., North Carolina; on Willis Mountain, Buckingham Co., Virginia.

References

  • Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
  • Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
Cite this article as: Geology Science. (2019). Kyanite. [online] Available at: http://geologyscience.com/minerals/kyanite/ [5th December 2019 ]
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