Mineral Information and Data:

Celsian
BaAl2Si2O8 [CNMNC approved formula]

Named after Anders Celsius (1701-1744), Swedish astronomer and naturalist.

IMA status : Valid species (Pre-IMA 1895) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
76.01.01.04  
  (76) Tectosilicate Al-Si Framework
  (76.01) with Al-Si frameworks
  (76.01.01) K (Na,Ba) feldspars
  
Nickel-Strunz
(10th edition) :
09.FA.30
  (09) Silicates
  (09.F) Tektosilicates without Zeolitic H2O
  (09.FA) Tektosilicates without additional non-tetrahedral anions
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 8.622(4) Å, b = 13.078(6) Å, c = 14.411(8) Å β = 115.2°
Crystal Habit: Crystals short prismatic, prism faces prominent; massive
  
Color: Colorless, white, yellow
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 6 to 6.5
Measured Density: 3.10 to 3.45 g/cm3
Cleavage: 3; {001} perfect, {010} good, {110} poor
Tenacity: Brittle
Streak: White
  
Polymorphism and Series: Dimorphous with paracelsian.
Geologic Setting: In amphibolite-grade, regional or contact metamorphic, Mn, Ba-rich rocks, some
of which probably were submarine exhalatives.
Mineral Association: Manganoan aegirine, manganoan biotite, paracelsian, jacobsite, hausmannite, rhodochrosite, rhodonite, rutile, hyalophane, barite, cymrite, taramellite, quartz, zoisite, spessartine, dolomite, muscovite
  
Synonyms/varieties: Barium-Anorthite (of Sjögren)
Comments: Forms series with hyalophane and orthoclase

 

Celsian
Chalky white macdonaldite, reddish brown taramellite
in peach colored celsian
Origin: Rush Creek district, Fresno Co., California, U.S.A.
Sample size: 5.5 x 7 x 4 cm
Photo: Dan Weinrich

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