. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. liwtiHiiiii, liirioJiitc, H'riH'iitim\ sefoudar^v in«giM;tit«' iirc ihc altiTaiioii miiierab (Fig-. 28). B(m,(- Angitp J ^^Onlv two occnrri'iu-es of basic augite yiti* were ohHorviMl. best!) as dikon culting^ t'lic biwcr piirts of the older «orii>s. 'l'b«' matrix of this nick is aphaiiitic and dark dull g?l?ayi^;h gTOcn. Small 2 mm. dark gn'oti. almost black. «H|iiaiit augiies and 5 mm. lailis of pal(3 grctiii f('kM|iar forjii tin? idieiiocrvsrs. The mieroHcopie aj)pO!)r^^ aiisY' of tla«8c ro
. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. liwtiHiiiii, liirioJiitc, H'riH'iitim\ sefoudar^v in«giM;tit«' iirc ihc altiTaiioii miiierab (Fig-. 28). B(m,(- Angitp J ^^Onlv two occnrri'iu-es of basic augite yiti* were ohHorviMl. best!) as dikon culting^ t'lic biwcr piirts of the older «orii>s. 'l'b«' matrix of this nick is aphaiiitic and dark dull g?l?ayi^;h gTOcn. Small 2 mm. dark gn'oti. almost black. «H|iiaiit augiies and 5 mm. lailis of pal(3 grctiii f('kM|iar forjii tin? idieiiocrvsrs. The mieroHcopie aj)pO!)r^^ aiisY' of tla«8c rocks is very similar to the aiignie andcsitcs tlnscidbcd above, from which they differ in the greatisr pereeiilage of femag raiiU'Tals. Thus in the aiigite aiickvites the ratio of and femags runs TO. twin mati( ht pr pleoe Fig. 2ik^^-^Olirinc frt:e bnmiU .weiiient uf the crystids is diabasie. rJienocrvHtH form about ¥) ])er of tlie rock. 'J'lie fehlsjmrs are <d' the aiidesiiH-labradorite variety. oligoeUise also oecuj's. The feldspars are tabular, irregrdarly led and '/a)Wa\, an<! contain inelusions of brown glass. They oceiir ?oiips and are strongly alTceted by chloritic alt»rations. As plamo- «; the feldspars bnnn ;'.0 per cent of the roek and, tlie angito 13 per The pbenocrvstie aiigites are tabular to et]uant, snbhodral, fresli 'Uiimlopliysie. In the groundrnass the feldspars are extremely pris- '., fresh and form 0 |)cr eiait. The of the groundrnass ("orm T eeot, are csquaiit, fresh, liighly ehaived, pale yellowish green, non- iroir* and ijit(\rstitial. Magnetite in large 4 mm. ecpiant grains. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York Academy of Sciences. New York, : The Academy
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1919
