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A catalog is presented of 1217 post-1890 published amphibole analyses which contain 6.00 per cent or more of CaO. Of these, 1106 are accompanied by at least one refractive index, an optic angle, or a density determination. With each analysis is given these physical constants; as well as the half-unit cell contents calculated on the basis of 24 (O, OH, F, Cl); the reference source; the locality; the mineral assemblage in which the amphibole occurs; whether any coexisting minerals have been analyzed; an indication of the quality of the analysis; and, to each amphibole, a name which conveys the composition rather precisely.

A rational nomenclature is proposed for these amphiboles, the naming of which is, at present, highly confused. The calciferous amphiboles are defined as those with Ca 1.50 and above in the half-unit cell, while the subcalciferous amphiboles contain between 1.00 and 1.50 Ca in the half-unit cell. The system proposed is based on the well-known end members tremolite, richterite, tschermakite, edenite, pargasite, and hastingsite. Three important variables define the main name to be given to an amphibole, namely the amounts of Si, Ca+Na+K, and Mg/Mg+Mn+Fe3+Fe2 in the half-unit cell. Prefixes then indicate the ranges of Na, Ca, Ti, AlVI, Mn, Cr, K, Cl, OH, and Fe3/Fe2. This avoids making new names other than those obtained by prefixing adjectives, retains the traditional meanings of the well-known end members and such terms as actinolite and kaersutite, dispenses with the need for the more obscure names, and enables the composition, with respect to no less than 15 variables, to be conveyed by the name.

Criteria to distinguish between good and poor amphibole analyses are suggested, discussed, and applied to the collection of amphibole analyses. Using these criteria, one third of the analyses appear to be of superior quality, one third of moderate quality, and the remaining third of inferior quality. Of recent analyses, roughly half are of superior quality. Therefore, even on a purely empirical basis, these criteria appear to be useful.

Frequency-distribution polygons show the ranges of composition and the most frequent compositions found in these amphiboles with respect to Fe3, Mn, Na, K, Ti, Ca, Si, OH, F, and Mg/Mg+Fe2+Fe3+Mn. A series of plots of analyzed amphiboles coexisting with analyzed clinopyroxenes, orthopyroxenes, biotites, garnets, and Ca-poor amphiboles summarizes the available information on these coexisting pairs and thus enables a number of interesting deductions to be made.

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