The Quarterly journal of the Geological Society of London . PossHinsects (IPurbecIc &StonesfidH. [Hg 20] J Quart Joura. Geo. Soc.~VolXxll8. JFoBsilJiiBects {JPurbeck &Iias CBg2J ) 1854.] DELESSE PEGMATITE. WOODWARD—H_PPURITIDiE. 397 6. On the Pegmatite of Ireland. By M. A. Delesse.[Abstract *.] The author observes that the Pegmatite of the Mountain of Mournein Ireland is very remarkable for its cavernous structure. Thisstructure is especially found in pegmatites which contain topazes ; itis therefore probable that the cavities in the pegmatite are owing tothe separation of fluoric gases, the f
The Quarterly journal of the Geological Society of London . PossHinsects (IPurbecIc &StonesfidH. [Hg 20] J Quart Joura. Geo. Soc.~VolXxll8. JFoBsilJiiBects {JPurbeck &Iias CBg2J ) 1854.] DELESSE PEGMATITE. WOODWARD—H_PPURITIDiE. 397 6. On the Pegmatite of Ireland. By M. A. Delesse.[Abstract *.] The author observes that the Pegmatite of the Mountain of Mournein Ireland is very remarkable for its cavernous structure. Thisstructure is especially found in pegmatites which contain topazes ; itis therefore probable that the cavities in the pegmatite are owing tothe separation of fluoric gases, the fluor of which is subsequentlyfixed in the topaz and mica. The Irish pegmatite is also very remarkable for the presence offayalite and of ferruginous peridote; for peridote is the characteristicmineral of rocks of igneous origin which have not an excess of quartz. M. Delesse remarks, in conclusion, that cavernous pegmatite isformed under circumstances markedly different from those underwhich granite properly so called is produced. May 24, GENERAL R. I. Murchison, Vice-President, in the Chair. 1. The Pres
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectgeology, bookyear1845
