A popular treatise on gems, in reference to their scientific value; a guide for the teacher of natural sciences, the jeweller, and amateur: together with a description of the elements of mineralogy, and all ornamental and architectural materials .. (1859)
Feuchtwanger, Lewis. [from old catalog] · New York, D. Appleton & company · leaf 43
angles ;in the second they intersect the middle edges equally; 36 A PEACTICAL TREATISE ON GEMS. and in the third they lie in an intermediate position, ordivide these edges unequally; the latter being hemihedralforms. These pyramids ar^ also distinguished as obtuse(fig. 25) or acute (fig. 26),…
Precious stones · Building stones · Mineralogy
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