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 . hundred poundswas found in the mud of a mining pit. Capital examples of itsassociation with galenite are shown, and the species is always in-structively illustrated in suites of specimens showing its varied ap-pearance and association. In recent years extraordinary beautiful specimens from have been found in green, blue, brown and yellow colors, andwith a variety of crystal forms of superb perfection. The baritesalways attrac
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 . hundred poundswas found in the mud of a mining pit. Capital examples of itsassociation with galenite are shown, and the species is always in-structively illustrated in suites of specimens showing its varied ap-pearance and association. In recent years extraordinary beautiful specimens from have been found in green, blue, brown and yellow colors, andwith a variety of crystal forms of superb perfection. The baritesalways attract observation; the aggregates of flat blue plates, thelong yellow to brown prisms, the white margined, square crystalsfrom Utah, the heavy plates from Cheshire, Conn., etc. Celestite, the sulphate of strontium, is a constant compan-ion of the sulphur of Girgenti, Sicily, and its white crystals deli-cately combined with the yellow of the sulphur form mineral speci-mens of great beauty. Celestite derives its name from the shadesof blue which in some specimens suffuse the crystals. In cabinetsexamples possessing this blue tint are shown from Strontian Is-. PECTOLITE W. Paterson, N. Collection, American Museum of Natural History GUIDE TO COLLECTIONS 191 land, Lake Superior. Some of these are often of remarkable is also shown with colemanite, from California. Gypsum, the sulphate of lime combined with water, is aprominent mineral and its transparent plates often enclosing foreigncrystallizations or displaying a satin sheen from its fibrous sur-faces (satin spar), are objects of beauty. The crystals from Po-land, Ohio, are characteristic; twinning is common and the so-called arrow-points (examples may be exhibited from Germany)are the result of this crystalline union. The crystals are fre-quently curved in their prolongations, and foamlike or crestedsprays are formed of considerable prettiness. The massive gyp-sum is found extensively in New York, Michigan and Nova S
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
