Information AboutDiabase |
| CATEGORIES ABOUT DIABASE | |
| igneous rocks | |
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Diabase normally has a fine, but visible texture of euhedral lath shaped Plagioclase Crystal s (62%) set in a finer matrix of Clinopyroxene , typically Augite (20 - 29%), with minor Olivine (3% up to 12% in olivine diabase), Magnetite (2%) and Ilmenite (2%).Klein, Cornelus andCornelius S. Hurlbut, Jr., 1986, ''Manual of Mineralogy'', Wiley, 20th ed., p. 483 ISBN 0-471-80580-7 Accessory and alteration minerals include Hornblende , Biotite , Apatite , Pyrrhotite , Chalcopyrite , Serpentine , Chlorite , and Calcite . The texture is termed ''diabasic'' and is typical of diabases. This ''diabasic'' texture is also termed ''interstitial''.Morehouse, W. W.,1959, ''The Study of Rocks in Thin Section'', Harper & Row, p. 160 The feldspar is high in anorthite (as opposed to albite), the calcium end member of the plagioclase Anorthite-Albite solid solution series, most commonly Labradorite . LOCATIONS Diabase is usually found in smaller relatively shallow intrusive bodies such as Dikes and Sill s. Diabase dikes occur in regions of crustal extension and often occur in dike swarms of hundreds of individual dikes or sills radiating from a single volcanic center. The Palisades Sill which makes up the New Jersey Palisades on the Hudson River , near New York City , is an example of a diabase sill. The dike complexes of the Hebridean Tertiary volcanic province which includes Skye, Rum, Mull, and Arran of western Scotland , the Slieve Gullion region of Ireland , and extends across northern England contains many examples of diabase dike swarms. DIABASE/DOLERITE In older British usage ''dolerite'' was preferred and ''diabase'' was used to refer to an ''altered dolerite''. Dolerite ( in his 1822 ''Traité de minéralogie''. In current geologic usage diabase is preferred.http://www.britannica.com/eb/article-9030242/diabase Encyclopedia Britannica Inscription controversy During seven centuries a diabase formation called Runamo was famous in Scandinavia as a Runic inscription, until it became the object of a famous scientific controversy in the first half of the 19th Century . REFERENCES |
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