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 . for the beams of light ina crystal and the planes in which thelatter are polarized. (Note: The teacher might consult largerworks for instruction upon the indieatrix and Fresnels ellipsoid,notably Prof. Henry A. Miers Mineralogy; an Introduction to theScientific Study of Minerals; Macmillan & Co.). Optical Anomalies are those variations from apparent opticallaws which many minerals display, and which often lead to a moreaccurate knowledg
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 . for the beams of light ina crystal and the planes in which thelatter are polarized. (Note: The teacher might consult largerworks for instruction upon the indieatrix and Fresnels ellipsoid,notably Prof. Henry A. Miers Mineralogy; an Introduction to theScientific Study of Minerals; Macmillan & Co.). Optical Anomalies are those variations from apparent opticallaws which many minerals display, and which often lead to a moreaccurate knowledge of their crystallographic construction. Thus some isometric minerals show double refraction, whilesome uniaxial crystals become biaxial; Garnet (isometric) showsdouble refraction, which has been assigned to the twinning of tri-clinic individuals, also Leucite (isometric), wdiich has been ex-plained by referring this seemingly cubic mineral to the tetragonalsystem. Chabazite (rhombohedral) possesses optical characterswhich have led to an hypothesis of twinning triclinic (tetragonal) shows biaxial phases; increase of temper-. Fig. 286 ? I ^ - 1 ^^^^^ ^1 B^^mhhI^^^^j^ . ^,. -t^ c/} w > H i-i 1—1 /, N hJ ?n o o >> H , ^ o C/3 f^ .- re o O pq 3
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
