|
Spessartine is a nesosilicate, manganese aluminium garnet species, Mn2+3Al2(SiO4)3.〔Gemological Institute of America, ''GIA Gem Reference Guide'' 1995, ISBN 0-87311-019-6〕〔〔〔 The name is a derivative of Spessart in Bavaria, Germany, the type locality of the mineral.〔〔 It occurs most often in granite pegmatite〔〔〔 and allied rock types and in certain low-grade metamorphic phyllites. Sources include Australia, Myanmar, India, Afghanistan, Israel, Madagascar, Tanzania and the United States.〔 Spessartine of an orange-yellow has been called ''Mandarin garnet'' and is found in Madagascar. Violet-red spessartines are found in rhyolites in Colorado and Maine. In Madagascar, spessartines are exploited either in their bedrock or in alluvium. The orange garnets result from sodium-rich pegmatites. Spessartines are found in bedrock in the highlands in the Sahatany valley. Those in alluvium are generally found in southern Madagascar or in the Maevatanana region. Spessartine forms a solid solution series with the garnet species almandine.〔〔 Well-formed crystals from this series, varying in color from very dark-red to bright yellow-orange, were found in Latinka, Rhodope Mountains, Kardzhali Province, Bulgaria. Spessartine, like the other garnets, always occurs as a blend with other species. Gems with high spessartine content tend toward a light orange hue, while almandine prevalence induces red or brownish hues.〔(Spessartite Garnet Gemological Information )〕 The mineral spessartite should not be confused with a type of igneous rock (a lamprophyre), which is called spessartite. Spessartine is called spessartite sometimes, a mistake. ==See also== * Garnet * Almandine * Andradite * Grossular * Pyrope * Tsavorite * Uvarovite * Geology * Mineral collecting * Mineral * Gemstone 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Spessartine」の詳細全文を読む スポンサード リンク
|