Loss of halogens from crystallized and glassy silicic volcanic rocks

Clay mineralogy of Pleistocene Lake Tecopa, Inyo County, California

“…The presence of lithium and fluorine in the present-day drainage suggests that these elements came from some other source than hot springs within the lake basin. Noble, Smith, and Peck (1967) presented fluorine analyses of 164 volcanic rocks of late Miocene or Pliocene age from southern Nye County, Nev., about 160 km north of the area under present study. The largest amount of fluorine in any sample was 1.40 per cent with the average value being about 0.13 percent.…”

Mineral resources of study areas contiguous to the Uncompahgre Primitive Area, San Juan Mountains, southwestern Colorado, with a section on interpretation of aeromagnetic data

“…The scattered high values, along with local occurrence of topaz in vesicles and fluorite along fractures, probably indicate that the original magma contained significant fluorine; the erratic but generally low values in devitrified rhyolite are interpreted to indicate general expulsion of fluorine during cooling and crystallization. Loss of fluorine during crystallization of rhyolitic magmas has also been documented by Noble, Smith, and Peck (1967) and by Lipman, Christiansen, and Van Alstine (1969).…”

Baseline geochemistry of soil and bedrock Tshirege Member of the Bandelier Tuff at MDA-P

“…The tentative finding that vitric and devitrified samples of the Tshirege Member have similar leachate chemistry is surprising (considering their large difference in bulk mineralogy and whole rock chemistry for some elements, pariicularly for C1-. Although whole-rock C1-is not available for background samples, vitric rocks typically contain five times higher C1-contents than devitrified rocks (Noble et al, 1967); yet the leachable C1-contents of vitric Units 4 and 5 are generally lower than those of devitrified Unit 4, following the general pattern of upward depletion within the Tshirege Member (Table 13). Apparently, the large amount of C1-that resides in glass within vitric rocks is unavailable to leaching.…”