Celestine (mineral)

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Celestine
Celestine - Sakoany deposit, Katsepy, Mitsinjo, Boeny, Madagascar.jpg
Clear grey-blue celestine crystals
General
CategorySulfate minerals
Formula
(repeating unit)
SrSO4 sometimes contains minor calcium and/or barium
IMA symbolClt[1]
Strunz classification7.AD.35
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnma
Unit cella = 8.359 Å,
b = 5.352 Å,
c = 6.866 Å; Z = 4
Identification
ColorWhite, Pink, Pale green, Pale brown, Black, Pale blue, Reddish, Greyish; Colourless or lightly tinted in transmitted light
Crystal habitTabular to pyramidal crystals, also fibrous, lamellar, earthy, massive granular
CleavagePerfect on {001}, good on {210}, poor on {010}
FractureUneven
TenacityBrittle
Mohs scale hardness3 - 3.5
LusterVitreous, pearly on cleavages
Streakwhite
DiaphaneityTransparent to translucent
Specific gravity3.95 - 3.97
Optical propertiesBiaxial (+)
Refractive indexnα = 1.619 - 1.622 nβ = 1.622 - 1.624 nγ = 1.630 - 1.632
Birefringenceδ = 0.011
PleochroismWeak
2V angleMeasured: 50° to 51°
DispersionModerate r < v
Ultraviolet fluorescenceShort UV=yellow, white blue, long UV=yellow, white blue
References[2][3][4][5]

Celestine (the IMA-accepted name)[6] or celestite[7] is a mineral consisting of strontium sulfate (SrSO4). The mineral is named for its occasional delicate blue color. Celestine and the carbonate mineral strontianite are the principal sources of the element strontium, commonly used in fireworks and in various metal alloys.

Etymology[edit]

Celestine derives its name from the Latin word caelestis meaning celestial [8] which in turn is derived from the Latin word caelum meaning sky or heaven.[9]

Occurrence[edit]

Celestine occurs as crystals, and also in compact massive and fibrous forms. It is mostly found in sedimentary rocks, often associated with the minerals gypsum, anhydrite, and halite.

The mineral is found worldwide, usually in small quantities. Pale blue crystal specimens are found in Madagascar. White and orange variants also occurred at Yate, Bristol, UK, where it was extracted for commercial purposes until the mid-20th century.[10]

The skeletons of the protozoan Acantharea are made of celestine, unlike those of other radiolarians which are made of silica.

In carbonate marine sediments, burial dissolution is a recognised mechanism of celestine precipitation.[11] It is sometimes used as a gemstone.[12]

Geodes[edit]

Celestine crystals are found in some geodes. The world's largest known geode, a celestine geode 35 feet (11 m) in diameter at its widest point, is located near the village of Put-in-Bay, Ohio, on South Bass Island in Lake Erie. The geode has been converted into a viewing cave, Crystal Cave, with the crystals which once composed the floor of the geode removed. The geode has celestine crystals as wide as 18 inches (46 cm) across, estimated to weigh up to 300 pounds (140 kg) each.

Celestine geodes are understood to form by replacement of alabaster nodules consisting of the calcium sulfates gypsum or anhydrite. Calcium sulfate is sparingly soluble, but strontium sulfate is mostly insoluble. Strontium-bearing solutions that come into contact with calcium sulfate nodules dissolve the calcium away, leaving a cavity. The strontium is immediately precipitated as celestine, with the crystals growing into the newly-formed cavity.[13][14][15]

See also[edit]

References[edit]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ Handbook of Mineralogy
  4. ^ Mindat.org
  5. ^ Webmineral data
  6. ^ "List of Minerals". 21 March 2011.
  7. ^ Nickel, Ernie.; Nichols, Monte. Mineral Names, Redefinitions & Discreditations Passed by the CNMMN of the IMA Archived May 30, 2008, at the Wayback Machine, Materials Data, 2004, p. 26. Celestine is the approved name for this mineral by the International Mineralogical Association Commission on New Minerals and Mineral Names (CNMMN). Although celestite finds frequent usage in some mineralogical texts, the name has been discredited as a valid mineral name by this organization.
  8. ^ "Celestine definition and meaning | Collins English Dictionary".
  9. ^ "Definition of CELESTIAL".
  10. ^ "Beneath our Feet | History of Yate | Home | Discover Yate's History at Yate Heritage Centre".
  11. ^ Baker, Paul A.; Bloomer, Sherman H. (1988). "The origin of celestite in deep-sea carbonate sediments". Geochimica et Cosmochimica Acta. 52 (2): 335–339. Bibcode:1988GeCoA..52..335B. doi:10.1016/0016-7037(88)90088-9.
  12. ^ Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens p.174
  13. ^ Anenburg, Michael; Bialik, Or; Vapnik, Yevgeny; Chapman, Hazel; Antler, Gilad; Katzir, Yaron; Bickle, Mike (2014). "The origin of celestine–quartz–calcite geodes associated with a basaltic dyke, Makhtesh Ramon, Israel". Geological Magazine. 151 (5): 798–815. Bibcode:2014GeoM..151..798A. doi:10.1017/S0016756813000800. S2CID 129529427.
  14. ^ Carlson, Ernest (1987). "Celestite replacements of evaporites in the Salina Group". Sedimentary Geology. 54 (1–2): 93–112. Bibcode:1987SedG...54...93C. doi:10.1016/0037-0738(87)90005-4.
  15. ^ Kile, Daniel; Dayvault, Richard; Hood, William; Hatch, H. Steven (2015). "Celestine-Bearing Geodes from Wayne and Emery Counties, Southeastern Utah: Genesis and Mineralogy". Rocks & Minerals. 90 (4): 314–337. doi:10.1080/00357529.2015.1034489. S2CID 130452012.

External links[edit]