MAKE A MEME
View Large Image
| View Original: | The_Quarterly_journal_of_the_Geological_Society_of_London_(12736739243).jpg (1866x3200) | |||
| Download: | Original | Medium | Small | Thumb |
| Courtesy of: | commons.wikimedia.org | More Like This | ||
| Keywords: The Quarterly journal of the Geological Society of London (12736739243).jpg 912 <br> T G BONNET ON THE SERPENTINE AND <br> projecting as happens with the gabbro of the Cuchullin Hills Skye <br> I have had slides cut from one of the dark bluish unweathered <br> specimens and from one of the exterior white and green The <br> former shows the rock to be an olivine gabbro There is plagio- <br> clase felspar generally in rather short irregularly oblong crystals <br> showing bright colours and twinning Some of these exhibit a pecu- <br> liar strongly marked cleavage or minute twinning with one set of <br> crystals dominating which gives them a general resemblance to the <br> structure of diallage The felspar is in places rather decomposed <br> There is a fair amount of diallage and a few crystals of common <br> augite These with ordinary light are as nearly as possible colour- <br> less and are in good preservation The olivine is rather rough in <br> texture and much cracked ; the cracks are marked out by a deposit <br> of granular opaque mineral probably magnetite which in some <br> cases appears to penetrate the intermediate spaces which are <br> commonly fairly translucent rendering them almost opaque ; now <br> and then it assumes a browner tinge as from haematite or limonite <br> and the grains are slightly stained with brown or green Most of <br> the olivine grains have a finely granulated aspect at the edges and <br> are sometimes bordered by a finely fibrous mineral probably ser- <br> pen tinous and a secondary product ; the grains however show <br> very little trace of conversion into serpentine Except the minute <br> granules described above there is very little magnetite or other <br> iron- oxide visible The above appearance would lead us to conclude <br> that the olivine is a rather ferruginous variety The other slide fig 7 <br> Fig 7 ” Diallage partly altered into Hornblende from outer part <br> of the great Gabbro mass at Coverack <br> A Decomposing felspar B Diallage C Hornblende <br> cut from a somewhat weathered mass which in appearance closely <br> resembled that of the veins exhibits plagioclase felspar beginning <br> to pass into the saussuritic mineral and diallage more or less con- <br> verted into minute hornblende but no olivine or serpentine that can <br> be recognized ” the slide on the whole being remarkably like one <br> cut from a vein on the shore at Coverack On closely examining 35819107 110705 51125 Page 912 Text 33 http //www biodiversitylibrary org/page/35819107 1877 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 33 1877 Geology Periodicals Smithsonian Libraries bhl page 35819107 dc identifier http //biodiversitylibrary org/page/35819107 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-24 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12736739243 2015-08-26 20 04 38 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1877 Photos uploaded from Flickr by Fæ using a script | ||||
.jpg){kind=link}
