Distribution of fluorine in unaltered silicic volcanic rocks of the western conterminous United States

Economic Geology
By: , and 

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Abstract

An investigation of more than 170 samples of glass-rich volcanic rocks of rhyolitic or rhyodacitic composition shows marked regional variations in the fluorine content. The uniformity of the class of rocks was controlled by index of refraction determinations on fused beads and by chemical analyses of about one-seventh of the total number. The fluorine content ranges from 20 to 4,900 ppm. The frequency distribution closely approaches a log-normal one; the median value is 520 ppm, the 90 percentile 1,820 ppm. The mean for 167 samples is 820 ppm. These correspond fairly well with earlier averages for similar types of rocks. The highest values are predominantly from a belt in central Colorado and west-central New Mexico, from the Big Bend region of Texas, and from southeastern Idaho and western Utah and northeastern Nevada. The distribution of the fluorine in these rocks correlates well with the distribution of significant fluorspar deposits and somewhat less well with areas where volcanic rocks are prevalent and ground waters carry large amounts of fluorine.

Publication type Article
Publication Subtype Journal Article
Title Distribution of fluorine in unaltered silicic volcanic rocks of the western conterminous United States
Series title Economic Geology
DOI 10.2113/gsecongeo.58.6.941
Volume 58
Issue 6
Year Published 1963
Language English
Publisher Society of Economic Geologists
Description 11 p.
First page 941
Last page 951
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