Having been asked to look at "cleaning up" pillars of dolomite so
that the galena can be more easily seen - a comment. When first
blasted you get the bright shiny surface that is easy to identify,
but as the ore is exposed it looses the shine, and over the years may
also pick up the dust etc that moves through the mine. thus after a
while it is not easy without re-cleaning the rock and removing the
surface material to easily identify the exact ore
Dave
>Barry Jones asks:
>
>"Would the lead miner in the 18th, 19th century be able to tell
>the quality of Galena in a vein by its texture and colour. Galena
>seems to very in colour from bright silver to dull browns. A lot
>of galena lies around spoil heaps - tailings today which seems
>to have been disregarded by the miner or surface workers. "
>
>I wonder if the mineral found in the dumps, varying in colour from
>bright silver to dull browns, could be sphalerite, not galena?
>
>Looking in my copy of Rutley's Mineralogy (24th edition, revised
>by H.H. Read) I see that, under galena, the comment on colour
>gives only one shade, "lead-grey". It also says "there are apparently
>no external characters which serve to distinguish even the highly
>argentiferous ores from ordinary galena -- the question can only
>be solved by analysis". It also adds "galena often occurs with blende"
>
>Under "blende, sphalerite, black jack" the author states, regarding
>colour, that blende is "usually black or brown, sometimes yellow or
>white and, rarely, colourless".
>
>The miners would have tended to reject sphalerite as, until the retort
>method of extracting zinc was introduced, it would not have yielded
>any metal in a furnace, merely a cloud of white smoke up the chimney.
>
>Tony Brewis
--
David A. Summers
Curators' Professor of Mining Engineering
Adjunct Professor of Nuclear Engineering
Director
Rock Mechanics and Explosives Research Center
University of Missouri-Rolla,
Rolla, MO 65409-0810
"fools talk, wise men listen." (a variant of Prov 12:23)
phone: (573) 341 4314
FAX: (573) 341 4368
related web pages
A growing selection of Dr. Summers' papers are being put on the Web
and can be accessed through the Bibliography
<http://campus.umr.edu/rockmech/people/summers/biography.html>
Rock Mechanics http://campus.umr.edu/rmerc/
Waterjet Lab: http://www.umr.edu/~waterjet/
UMR Stonehenge: http://www.umr.edu/~stonehen/
Personal: http://www.umr.edu/~rockmech/data/Summers.html
Mining Eng. http://www.umr.edu/~mining/
Waterjet Assoc http://www.wjta.org/
International Waterjet Society: http://www.iw.uni-hannover.de/iswjt/
Next American Waterjet conference: http://www.wjta.org/conference.htm
7th Pacific Rim Conference (May 2003) http://www.kojet.org
Distance Learning: http://campus.umr.edu/mining/ogeneral.htm
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