Celestine (mineral)

Celestine
Clear grey-blue celestine crystal
General
Category Sulfate minerals
Formula
(repeating unit)		 SrSO4 sometimes contains minor calcium and/or barium
Strunz classification 7.AD.35
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pnma
Unit cell a = 8.359 Å,
b = 5.352 Å,
c = 6.866 Å; Z = 4
Identification
Color Colorless, white, pale blue, pink, pale green, pale brown, black
Crystal habit Tabular to pyramidal crystals, also fibrous, lamellar, earthy, massive granular
Cleavage Perfect on {001}, good on {210}, poor on {010}
Fracture Uneven
Tenacity Brittle
Mohs scale hardness 3 - 3.5
Luster Vitreous, pearly on cleavages
Streak white
Diaphaneity Transparent to translucent
Specific gravity 3.95 - 3.97
Optical properties Biaxial (+)
Refractive index nα = 1.619 - 1.622 nβ = 1.622 - 1.624 nγ = 1.630 - 1.632
Birefringence δ = 0.011
Pleochroism Weak
2V angle Measured: 50° to 51°
Dispersion Moderate r < v
Ultraviolet fluorescence Short UV=yellow, white blue, long UV=yellow, white blue
References [1][2][3][4]

Celestine or celestite[5] 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

Celestine derives its name from the Latin word caelestis meaning celestial,[6] which in turn is derived from the Latin word caelum meaning sky or heaven.[7]

Occurrence

Celestine from the Machow Mine, Poland.
Celestine mineral on display at Yale's Peabody Museum

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.

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.[8] It is sometimes used as a gemstone.[9]

Geodes

Celestine geode section
Inside the Crystal Cave geode in Ohio

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 highly 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.[10][11][12]

See also

References

  1. ↑ Mineralienatlas
  2. ↑ Handbook of Mineralogy
  3. ↑ Mindat.org
  4. ↑ Webmineral data
  5. ↑ 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.
  6. ↑ https://www.collinsdictionary.com/dictionary/english/celestine
  7. ↑ https://www.merriam-webster.com/dictionary/celestial
  8. ↑ 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.
  9. ↑ Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens p.174
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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.
  • Wikisource "Celestine". Encyclopædia Britannica. 5 (11th ed.). 1911.
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