. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. : SCIENTIFIC )><vu\:ey OF POBTO jnco dioi'ites, respecii\'ely. arc groupcil togetlier. Pekitic rocks of tliis oom- position are ©(.'casicvnallv foiind. Th(3y consiBt chiefly ol' quartz iind limo- soda ;par with iiotidile amounts of ]H)tasli feldspar and siibordjiiato l'erroM'ia«iiicsiaji mineraL«. Sucli rocks are also known as dollcnitcs.^ A tvpical example of this group is to he torind Jiortli of Aguas Bneiiap. The speciinciis (;oliected consisted of pJieoocrysts of quartz, feldspar, predonii- n
. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. : SCIENTIFIC )><vu\:ey OF POBTO jnco dioi'ites, respecii\'ely. arc groupcil togetlier. Pekitic rocks of tliis oom- position are ©(.'casicvnallv foiind. Th(3y consiBt chiefly ol' quartz iind limo- soda ;par with iiotidile amounts of ]H)tasli feldspar and siibordjiiato l'erroM'ia«iiicsiaji mineraL«. Sucli rocks are also known as dollcnitcs.^ A tvpical example of this group is to he torind Jiortli of Aguas Bneiiap. The speciinciis (;oliected consisted of pJieoocrysts of quartz, feldspar, predonii- naid-lv the lime^sodu Tarieiv, and mica., in a finc-graiiied oTouiidmass. This rook oeeurs associated witli otlier acidic rocks of almost tiie !?ame composition^ and is (k)uhtless merely a difrert'n,tiated fdiase of .some hirgcr ijdTiisive. QUAirrZ ^^lUKZONlTKS Tliose are granitoid rocks consisting chiefly of (piartz, mediirm phigio- clasc, witli consideraliJc orthoclase. With these may octair l)iotite, Ikji'ii- hleiide, or pyi-oxeiie. The)' are the closest associates of tlie grairites ami. 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
