Ask A Scientist Chemistry Archive

name         Sam M.
status       student
age          12

Question -   How would you extract zinc out of zincblende?
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This is a good opportunity to explore some things about minerals in
general. Zinc blende (two words) is another name for the mineral
"sphalerite". The "simple" composition is ZnS, but is seldom appears in
the pure form. The most common co-cation is iron in varying ratios, so the
"composition" is frequently written (Zn/Fe)S. In addition, more often than
not, a mineral may be imbedded in another mineral, or the other way
around. The technical terminology might be "sphalerite in a matrix of
pyrite".
     In the world of mineralogy, rocks, ores, and gems often have "common"
names that tell you nothing about the nature of the substance. It may be
named for the person or place that the mineral was first discovered. A given
mineral very frequently has several names.
     Two inexpensive references for rocks, minerals and gems are: "Simon &
Schuster's Guide to Rocks and Minerals" (ISBN 0-671-24417-5) and "Simon &
Schuster's Guide to Gems and Precious Stones"
(ISBN 0-671-60430-9) cost only $17 and $16 respectively and packed with
beautiful color photos on every page. There are also many web sites, one is:
http://www.minerals.net/index.htm.
     Because of safety issues, I would not generally reply with a separation
method to anyone under the age of 21; however, since the procedure is
readily available in books and on the Internet it is not hard to find, so it
is better to spell out the dangers rather than attempting to hide what is
already common knowledge anyway. The mineral is soluble in hydrochloric
acid,  giving off hydrogen sulfide fumes. WARNING: Hydrogen sulfide is
EXTREMELY TOXIC. Hydrochloric acid fumes are EXTREMELY IRRITATING to skin
and lungs. The procedure should only be attempted with very small samples,
and only with the supervision of an adult WHO KNOWS THE HAZARDS AND HOW TO
AVOID THEM.
     I advise Sam M. NOT to be adventurous and try this, if there is not any
reason (other than curiosity) to attempt this hazardous procedure. H2S and
HCl are really nasty and dangerous to handle without the proper lab setup.

Vince Calder
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