A popular guide to minerals : with chapters on the Bement Collection of minerals in the American Museum of Natural History, and the development of mineralogy . rismatic faces are par-allel to the vertical axis. This orthorhombic prism then is eitherbrachy or macro-prismatic by the introduction of the variable nwhich reckoned on the brachy or macro diagonal gives rise to therespective prisms cc P n and oo P n. The pinacoidal formulae are self-evident, as faces which arethe limital expression of a prismatic face, or n becomes oo, withreference, according to the pinacoid considered, to the brachy
A popular guide to minerals : with chapters on the Bement Collection of minerals in the American Museum of Natural History, and the development of mineralogy . rismatic faces are par-allel to the vertical axis. This orthorhombic prism then is eitherbrachy or macro-prismatic by the introduction of the variable nwhich reckoned on the brachy or macro diagonal gives rise to therespective prisms cc P n and oo P n. The pinacoidal formulae are self-evident, as faces which arethe limital expression of a prismatic face, or n becomes oo, withreference, according to the pinacoid considered, to the brachy ormacro diagonal. Combinations of Orthorhombic Forms. Plate 5 illustrates the union in single crystals of the ortho-rhombic forms just reviewed. EXPLANATION OF PLATE 5. Fig. 121, Two prisms and pyramid (topaz) ; Fig. 122, Prisms,pyramid and dome (ilvait) ; Fig. 123, Basal brachy and macro pin-acoid; Fig. 124, Two pyramids of different inclinations, dome, andbasal pinacoid (sulphur) ; Fig. 125, Basal pinacoid, and domes; , Basal pinacoid and domes; Fig. 127, Basal pinacoid, prisms,and domes (the last three are baritc) ; Fig. 128, Three pinacoids,. GALENA Galena, Ills. Bement Collection, American INIuseum of Natural History DEFINITION OF TERMS -7
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
