touristic (toristik)

[ Curiously enough, there is no such thing as a record of touristic journeying in Crete. Lord Str any ford , Letters and Papers, p. 98. (Davies.) tour mal in, tourmaline (tör'ma-lin), n. [Also turmalin , turm a line ; tourmaline = Sp. tur malina = It. turmalina , tormalina (NL. turmali na, turmalinus ); said to be tournamal , a name given to this stone in Ceylon.] A mineral, crystallizing in the rhombohedral system, often in the form of a three-, six-, or nine-sided prism terminated by three faces of an obtuse rhombohedron. It often exhibits hemimorphism, the opposite extremities of a prismatic crystal showing an unlike development of planes. Its fracture is uneven or conchoidal; its hardne is a little greater than that of quartz. In composition tour mal in consists principally of a borosilicate of aluminium and magnesium, but contains frequently iron, lithium, and other elements. Some varieties are transparent, some translucent, some opaque. Some are colorle , and others green, brown, red, blue, and black, the last being the most common. Not infrequently the color varies in different parts of the crystal: thus, there may be a green exterior part about a red nucleus, or a crystal may be red at one end and green at the other, etc. Achroite is a colorle variety from Elba: rubellite is a pink or red variety containing lithium; indicolite is a blue or bluish-black variety; aphrizite is a black variety from Norway. Common black tour mal in is often called schorl. The transparent red, green, blue, and yellow varieties are used in jewelry: here belong the Brazilian sapphire, the Brazilian emerald, etc. Tour mal in occurs most commonly in granite, gnei , and mica-schist. It is found in England, Scotland, Sweden, America, Spain, Siberia, and elsewhere. Sections cut from prisms of tour mal in are much used in polarizing apparatus. (See polariscope.) It exhibits marked pyro-electric phenomena, which are connected with its hemimorphic crystalline structure. See pyro - electricity. - Tour mal in plates. Same as tourma lin tongs. See polariscope. - Tour mal in tongs. See po lari scope. tour mal in-granite (tör'ma-lin-gran"it), n. A variety of granite containing, in addition to the other usual ingredients, tour mal in, and more tour mal in-granite generally black tour mal in or schorl. Such granites are very common in various tin-producing districts, and especially in Cornwall. See schorl and schorlaceous. tournt, v. An obsolete form of turn.