I have been
aware of mineral sublimates (materials or minerals formed by direct solid deposition
from gas) for a long time from research of friends and colleagues at Dartmouth
College on fumarolic sublimates at Izalco volcano in El Salvador. Early
collection of minerals there occurred in the 1960’s before and after the 1966
eruption of Izalco*. Vanadates and copper vanadate minerals were found among
the sublimates, including several newly identified minerals. For a few of the
new sublimates, I, having microscope reflectance measurement experience through coal petrography work,
contributed the mineral reflectivity data required for naming new opaque
minerals.**
Izalco volcano, El Salvador (this photo and one below from Smithsonian Institution Global Volcanism Program) |
Belkin
related that one of Finkelman’s early publications (1987; citation below) was
on his description of new mineral, downeyite, the first confirmed natural occurrence
of selenium oxide. Downeyite
is a sublimate formed near a
hot gas vent, but not at a volcano: it was found on a burning culm heap in the
Northern Anthracite field of Pennsylvania! Piled coal or coal waste can smolder
or spontaneously combust. I previously wrote in 2015 about culm heap fires in northeastern Pennsylvania, and evidence that a coal fire in one of the coal bunkers on the Titanic was a possible reason for the speed of passage
(easiest way to stop a bunker coal fire is to shovel down and use up coal).
Fell Township, PA, coal waste dump fire, February 2014. (The Scranton Times-Tribune) |
Forestville coal dump where downeyite first found. (From PA Geological Survey, Mineral Resource Report 78, 1980) |
Downeyite
is acicular, colorless and extremely hygroscopic, so, as described in Finkelman and Mrose (1977), must be immediately put in a desiccator upon removal
from the hot dry vent environment. Temperatures where downeyite was deposited
were 190-230˚C. Over twenty other
minerals found at “anthracite smokers”, as vents of hot gas on culm heaps or
over underground mine fires are called (Stracher, 1995), are detailed in
Pennsylvania Geologic Survey Mineral Resource Report 78 (citation and download
link below), including crystals of elemental selenium. That report indeed does cite
the similar occurrence of sublimates at volcanic fumaroles including Izalco!
(From PA Geological Survey, Mineral Resource Report 78, 1980) |
Finkelman,
“Anthracite smoker” references
Finkelman, R. B., Mrose, M. E.,
1977, Downeyite, the first verified natural occurrence of SeO2: American Mineralogist, v. 62, n. 3-4, p.
316-320. (https://pubs.geoscienceworld.org/msa/ammin/article-abstract/62/3-4/316/40741/downeyite-the-first-verified-natural-occurrence-of?redirectedFrom=fulltext)
Lapham,
Davis M., Barnes, John H., Downey, Wayne F., Jr., Finkelman, Robert B., 1980,
Mineralogy associate with burning anthracite deposits of Eastern Pennsylvania: Mineral Resource Report 78, Pennsylvania
Geological Survey, Fourth Series, Harrisburg, 92 pages. (Can download from this
page- scroll down to “M 78”: http://www.docs.dcnr.pa.gov/topogeo/publications/pgspub/mineral/index.htm
)
Stracher,
Glenn, B., 1995, The anthracite smokers of eastern
Pennsylvania: PS2(g) -T stability diagram by TL analysis: Mathematical Geology, v. 7, n. 4,
p. 499-511 (https://link.springer.com/article/10.1007/BF02084424)
Izalco
references
*Rose,
W. I., Stoiber, R. E., 1969, The 1966 eruption of Izalco Volcano, El Salvador: Journal of Geophysical Research, v. 74,
n. 12, p. 3119- 3130.
Stoiber,
R. E., Rose, W. I., Jr., 1974, Fumarole incrustations at active Central
American volcanoes: Geochimica et
Cosmochimica Acta, v. 38, p. 495-516.
**Hughes, J. M.,
Drexler, J. W., Campana, C. F., Malinconico, M. L., 1988, Howardevansite, (Na,
K)CuFe2(VO4)3, a new
fumarolic sublimate from Izalco Volcano, El Salvador, Descriptive mineralogy
and crystal structure: American
Mineralogist, v. 73, p. 181-186.
Hughes, J. M.,
Starkey, S., Malinconico, M. L., and
Malinconico, L. L., Jr., 1987, Lyonsite, Cu3Fe4(VO4)O6, a new fumarolic sublimate from
Izalco Volcano, El Salvador, Descriptive mineralogy and crystal structure: American Mineralogist, v. 72, p. 1000-1005.
Robinson, P. D.,
Hughes, J. M., Malinconico, M. L.,
1987, Blossite, alpha-Cu 2V2O7, a new
fumarolic sublimate from Izalco Volcano, El Salvador, Descriptive mineralogy
and crystal structure: American
Mineralogist, v. 72, p. 397-400.
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