Datolite on sphalerite from San Luis Potosí, Mexico (size: 6.2 x 5.3 x 2.8 cm)
General
Category
Nesosilicate
Formula (repeating unit)
CaBSiO4(OH)
IMA symbol
Dat[1]
Strunz classification
9.AJ.20
Crystal system
Monoclinic
Crystal class
Prismatic (2/m) (same H-M symbol)
Space group
P21/c
Unit cell
a = 9.62, b = 7.6 c = 4.84 [Å]; β = 90.15°; Z = 4
Identification
Color
Colorless or white; may be grayish, yellow, green, pale green, red, pink, etc.
Crystal habit
Crystal prismatic, short to tabular; Botryoidal or globular with columnar structure; granular to compact; cryptocrystalline
Cleavage
None
Fracture
Conchoidal to uneven
Tenacity
Brittle
Mohs scale hardness
5 to 5.5
Luster
Vitreous, rarely subresinous on fracture surface
Diaphaneity
Transparent to translucent, rarely opaque
Specific gravity
2.96 – 3.00
Optical properties
Biaxial (-)
Refractive index
nα = 1.626 nβ = 1.653 - 1.654 nγ = 1.670
Birefringence
δ = 0.044
2V angle
Measured: 74°
Dispersion
r > v; weak
Ultraviolet fluorescence
Fluoresces blue under SW UV
References
[2][3][4]
Datolite is a calcium boron hydroxide nesosilicate, CaBSiO4(OH). It was first observed by Jens Esmark in 1806, and named by him from δατεῖσθαι, "to divide," and λίθος, "stone," in allusion to the granular structure
of the massive mineral.[5]
Datolite crystallizes in the monoclinic system forming prismatic crystals and nodular masses. The luster is vitreous and may be brown, yellow, light green or colorless. The Mohs hardness is 5.5 and the specific gravity is 2.8 - 3.0.
Polished datolite nodule from the Quincy Mine of Michigan’s Copper Country (size: 4.1 x 3.3 x 1.7 cm)
The type localities are in the diabases of the Connecticut River valley and Arendal, Aust-Agder, Norway. Associated minerals include prehnite, danburite, babingtonite, epidote, native copper, calcite, quartz and zeolites. It is common in the copper deposits of the Lake Superior region of Michigan. It occurs as a secondary mineral in mafic igneous rocks often filling vesicles along with zeolites in basalt. Unlike most localities throughout the world, the occurrence of datolite in the Lake Superior region is usually fine grained in texture and possesses colored banding. Much of the coloration is due to the inclusion of copper or associated minerals in progressive stages of hydrothermal precipitation.
^One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Datolite". Encyclopædia Britannica. Vol. 7 (11th ed.). Cambridge University Press. p. 846.
Datolite is a calcium boron hydroxide nesosilicate, CaBSiO4(OH). It was first observed by Jens Esmark in 1806, and named by him from δατεῖσθαι, "to divide...
basalts and diabase and in serpentinites in association with zeolites, datolite, prehnite, calcite and serpentine. It is found in a wide variety of worldwide...
Though not a zeolite, prehnite is found associated with minerals such as datolite, calcite, apophyllite, epidote, stilbite, laumontite, and heulandite in...
with a new mineral which he found in Arendal, Norway. In 1806 he named datolite, from the Greek word meaning "to divide". This was a reference to the granular...
fluoric vapors from the granite they may contain much axinite, fluorite and datolite, but the altiminous silicates are absent from these rocks. From diabases...
with these other minerals: willemite, rhodonite, pyrochroite, hedyphane, datolite, and baryte. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical...
Watchungs and typically, are seen as embedded nodules along exposed fronts. Datolite, another nodular mineral, has been found embedded in the volcanic rock...
Manganese Field, Northern Cape, South Africa where Inesite is associated with datolite, pectolite, apophyllite, ruizite, orientite and quartz. Broken Hill, New...
associated minerals can occur with specimens from Franklin: axinite, rhodonite, datolite, willemite, , bustamite, charlesite, clinohedrite and roeblingite. Warr...
initially examining their synthesis (including the synthesis of boracite and datolite) and then examining pyroelectricity in scolecite along with Georges Friedel...
Gratiot Copper mine - Gratiot location, Keweenaw County Dana mine - Central Datolite mine - Isle Royale, Keweenaw County Delaware mine - the abandoned town...
oyelite, hematite, celestine, sturmanite, and poldervaartite, baryte, datolite,andradite, thaumasite, caryopilite and gageite. Not only is it a rare mineral...
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