Teaching Atlas of Nuclear Medicine (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Mineral.Water of ConstitutionSpecific Gravity.Garnet0 per cent.3-2?4-3Olivine -n.A uO i 3Q.C 1 generally ) less thanl O OHornblende3 - - -( rarely, 2 )3Muscovite - - - -4-082-9Chlorite - - - -12-112-8Serpentine - - - -13-08,2.61 Chondrodite (of close mineral affinities with olivine) contains no water. VUlarsite, which agrees with olivine in crystal form and optical characters, contains 4 to 6'2 per cent, of water, with a corresponding diminution of density to 3'04. 2 Occasionally a trace of water, rarely as much as 1 per cent. 3 Weathered varieties are found to contain 3 to 20 por cent. The obvious general conclusion on this point would seem to be, that though pressure acting hydrostatically is favourable to crystallization it can only be safely asserted to promote this by way of a metatropic alteration of bodies whose chemical composition has been previously determined by various para- morphic agencies; that its action in this respect is limited to those cases in which crystallization is accompanied by increase of density of the body which crystallizes; and that this stops a long way short of what is required of it to bring about those vast and complicated changes which are implied in the ' metamorphism' of clastic sedimentary rocks into crystalline schists and gneiss. iv. METATAXIS. This term has been already defined as connoting alterations in the relative positions of the constituents of a rock-mass; and the developeinent of slaty cleavage, which is now pretty generally recognized as a result of mechanical force, has been instanced as typical of metataxic change. a. Cleavage.?The recent exhaustive paper on this subject by Mr. Harker has put the matter in a very clear light. While agreeing with that author in his general treatment of the subject, and in h...