page_title: Datolite
hierarchical_section_title: Datolite
caption_attribution_description: English: Datolite Locality: Charcas, Municipio de Charcas, San Luis Potosí, Mexico (Locality at mindat.org) Size: small cabinet, 6.2 x 5.3 x 2.8 cm Datolite Perched on a sliver of sphalerite and a smaller crystal of datolite is a superb, well formed, translucent, sea-foam-green crystal of datolite, measuring 4.5 cm across. Alternating faces of matte luster and glassy luster add to the sharp form of this specimen. For crystallography, these old datolites really are highly desirable, but so seldom seen. Romero had 2 of the best I know of, this and another, with sharp crystal habit and excellent aesthetics compared to the usual jumbled plates which came out (perhaps 20 years or more ago). An elegant example of this species, from a locale that most folks simple have never seen one from. Ex. Dr. Miguel Romero Collection. Deutsch: Datolith Fundort: Charcas, Municipio de Charcas, San Luis Potosí , Mexiko (Fundort bei mindat.org) Größe: 6.2 x 5.3 x 2.8 cm
context_page_description: Datolite is a calcium boron hydroxide nesosilicate, CaBSiO₄. 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.
  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.
  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.
context_section_description: 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.
  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. 
  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.
  Botryolite is a botryoidal form of datolite.
caption: Datolite on sphalerite from San Luis Potosí, Mexico (size: 6.2 x 5.3 x 2.8 cm)
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