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Ca2(Mg,Al)5(Si,Al)8O22(OH)2
Monoclinic
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| Figure 17-39. Superb euhedral crystals of hornblende (black) in calcite (white) from Franklin. Specimen is 10 cm in maximum dimension. Smithsonian Institution, #R3208-4. Photo by the author. | ||
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Hornblende, a calcium magnesium iron aluminum silicate hydroxide mineral of the amphibole group, was first reported from Franklin by Nuttall (1822) who named it maclurite.
Hornblende was encountered in specimens from both Franklin and Sterling Hill during the writer’s analytical studies of local amphiboles. The crystals are commonly euhedral, dark-green to nearly black, and commonly 1-3 cm in size. Some are much larger, up to 15 x 45 cm according to Palache (1935) (Figure 17-39). These are mostly pargasitic or edenitic hornblende. An analysis of black euhedral crystals from Sterling Hill is given in Table 12.
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| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
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Link
to homepage
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This
page created: January 11, 2001 |
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