Datolite

Datolite is named after Greek "datysthai" - to divide, alluding to the granular habit of some massive specimens.

Datolite can be yellow, brown, light green, colourless, pink, red and violet. It forms prismatic crystals and nodular masses. Transparent crystals are faceted into brilliant stones and opaque massive material is cut into cabochons. Facet grade rough rarely exceeds 2 g.

Datolite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 

Datolite Gemstones by Size

This table shows distribution of Datolite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.26 cts
Heaviest:7.85 cts
Average:2.18 cts
Total photos:12
Do you have a larger Datolite? Why not upload a photo?
0.26ct to 1.02ct1.02ct to 1.78ct1.78ct to 2.54ct2.54ct to 3.30ct3.30ct to 4.06ct4.06ct to 4.81ct4.81ct to 5.57ct5.57ct to 6.33ct6.33ct to 7.09ct7.09ct to 7.85ct
General Information
Chemical Formula
CaBSiO
 
4
(OH)
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Datolite
Mohs Hardness5 to 5.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.90 to 3.00
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Cleavage QualityNone
Arthur Thomas, Gemstones (2009)
FractureConchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Datolite
Refractive Index1.621 to 1.675
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterBiaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.044 to 0.045
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) DoublingMore from other references
PleochroismNil
Arthur Thomas, Gemstones (2009)
Dispersion0.016
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Yellowish, greenish, colourless, white, orange-brown
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTransparent,Translucent
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Inert to blue
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Fluorescence (Short Wave UV)Inert to blue
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Crystallography of Datolite
Crystal SystemMonoclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitCharacteristic short prismatic crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Datolite occurs as a secondary mineral in mafic igneous rocks, in geodes in tuffs or skarns in limestones, in serpentinites and hornblende schists and in some ore veins.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Datolite information at mindat.org
Significant Gem Localities
Mexico
 
  • San Luis Potosí
    • Mun. de Charcas
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 403
Russia
 
  • Primorsky Krai
    • Dalnegorsk Urban District
USA
 
  • Massachusetts
    • Hampden Co.
      • Westfield
    • Hampshire Co.
      • Amherst
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 403
  • Michigan
    • Keweenaw Co.
      • Lake Superior
Copyright © Jolyon & Katya Ralph 1993-2018. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.