Identifier: buildingdecorati00merr (find matches)
Title: The building and decorative stones of Maryland, containing an account of their properties and distribution
Year: 1898 (1890s)
Authors: Merrill, George P. (George Perkins), 1854-1929 Mathews, Edward Bennett, b. 1869
Subjects: Stone Building stones
Publisher: Baltimore, Johns Hopkins press
Contributing Library: The Library of Congress
Digitizing Sponsor: Sloan Foundation

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be representative: Calculated percentajies, from chemical Percentajies obtained bj- speciilc gravity analyses. separation. Quartz 40.0 Sp. gr. Orthodase 9.0 3.6.5 (Quartz) 40.0 Albite molecules 35.8 3.5.5-3.04 ( p^i^i 45 q Anorthite l.3.6 3.67-3.8 ) Biotite 9,7 ; Biotite, 1 ,„„ T. .J ^ ., „ Above 3.8-,^ ... 15.0 Epidote 0.9 I Epulote, t A microscopic study of sections from the Port Deposit graniteshows the presence of the usual granitic minerals, such as quartz,feldspar, dark and light micas, apatite, zircon, sphene, allanite, epidote,chlorite, hornblende, magnetite, garnets and occasionally calcite. Thequartz is in relatively large sized areas, ranging from 0.5 mm. x 1.5mm. to 3 mm. x 5 mm. With the aid of the microscope these area.-!are seen to be not single units, but composed of a great number ofsmall quartz fragments, which have resulted from the crushing andrecrystallization of the original granite during the period when the MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE X.
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•J 3 MARYLAND GEOLOGICAL SURVEY 143 rock received its present schistose structure. These smaller quartzfragments are aggregated together by intricat interlocking suturesin a way which renders the rock less rigid and at the same time capableof withstanding fully as much pressure as an individual grain. Theinterstitial areas between the fragments of the coarser mosaic arefilled with a mosaic of still smaller grains. Occasionally the quartzshows small inclusions of iron oxide, dust-like particles and quartzneedles, although it usually appears exceptionally free from them.After a study of several sections from tlic Mc(lanahan quarry thepresent writer is inclined to think that the estimated proportion oftlie alkaline and plagioclase feldspar may better represent the char-acter of the rock of the area, and that the figures obtained from theanalysis and the slides indicate a greater amount of the more solubleplagioclase feldspar than the average run of the quarry. If the in-ference

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