Danger in the Cullen Hall of Gems and Minerals - Houston Gem ...

Danger Stalks the Cullen Hall of Gems and Minerals
Or,
Just when you think it’s safe to enter the Hall….
by Neal “Ghostwriter” Immega
Written in 2004 for use in the Minerals Hall documentation
Submitted by Neal Immega for use on the HMNS Volunteer Website on 3/11/08
If only you knew – and I am going to tell you!
Sharp Dealing: Did you know that our prize, bright red rhodochrosite (Case 77) was the cause
of a falling out between friends The story reputedly goes like this. Some young “recreational
prospectors” were collecting in the abandoned Sweet Home silver mine for rhodochrosite. They
agreed that whatever they found would be shared but that was before blasting opened a pocket
containing, among others, the amazing fist sized, single crystal. After what was likely a really
good party, they went to sleep that night in the tunnel. Next morning, they woke to discover that
the one of their company had had left -- with the crystals.
The specimen eventually arrived in the hands of a big time dealer, who sold it in the 80s for
$85,000 to Perkin Sams (the founder of our collection). At the time, the specimen was called the
“most attractive mineral specimen in the world.” That title might have been a little hyped but the
specimen is really fine.
Rhodochrosite from the Alma mine, Colorado
Page 1 of 8

Poison: Remember that chemistry class you took a thousand years ago, when they told you that
heavy metal salts are generally brightly colored It is true. Just like snakes, the brightly colored
ones are deadly. Some of our most colorful minerals are poisonous. As an example of this, look
at the case of lead minerals in near the front of the hall (Case 11). The primary mineral is dull
gray galena (lead sulfide). This is the primary ore of lead and is very common in the Missouri
lead belt. When it weathers, the lead combines with other elements to make bright secondary
minerals like orange wulfenite (lead molybdate), brick red vanadenite (lead vanadate), and
crocoite (lead chromate). I always take my tours to the lead case and remind them that they could
handle these specimens safely if they would wash their hands afterward. The mothers always
smile at that.
Galena
Page 2 of 8

Crocoite from Tasmania
Greed and Death: In the back of the hall, you can see the display (Case 126) containing the
Denny Mountain, Washington, sceptered amethyst quartz cluster. Each scepter is made up a
milky quartz crystal with a larger amethyst quartz crystal growing on its end, so that it looks like
a royal scepter. There is a railroad cut through Denny Mountain which exposes cavities in basalt
which contain these crystals. Mineral collectors rappel down the cliffs to the holes and hang on
to probe in them. Many of these people are not rock climbers and do not take sufficient care to
clean the cliff of rock that can fall off. Often the collectors do not even have hard hats on. A
Page 3 of 8

1985 article in the Mineralogical Record reported that the local Seattle collectors knew of 20
men who have died at this locality.
Quartz from Denny Mountain, Washington
Crystal scepters are rather uncommon. A quartz crystal is typically much longer than it is wide
because the six triangular faces at the end grow much faster than the prism faces. If these faces
are contaminated (usually by organic acids), the crystal will stop growing. If the crystal starts
growing again, it will be from the tip because that is the most active site. The new crystal will
grow both upward and back down over the old crystal and it will be bigger than the old one, i.e.
septered. It was just a lucky accident that the chemistry of the solution changed so that the new
crystal became amethyst. Sometimes, the new crystal may not stick very well to the poisoned old
one and the tip can be pulled off like a cap.
Arsenic and Old Minerals: Color is not a very useful way to identify minerals. If you look at
the adamite in the zinc case (#27), you will see that it can be a very pretty and gemmy
purple.When slightly weathered, it becomes yellow legrandite of nearly identical composition.
Many zinc compounds are not poisonous, for example the zinc oxide used in diaper rash creams
for babies and that white sunscreen for your nose. Adamite and legrandite, though, would make
an excellent slow poison because their composition is zinc arsenate.
Page 4 of 8

Adamite
Poison, Greed and Death: Want to know the worst mineral on 3 different criteria Cerrusite is
lead carbonate and is one of the more poisonous minerals in the hall and one of the most
beautiful. There are a number of cerussite specimens of this mineral in the hall that look like
snowflakes but the one I want to point out is in the right front side of the hall (Case 18). It looks
like a diamond with its lovely colored sparkle and you should see how it reflects a laser light!
Lead carbonate is so dangerous because it is soluble in stomach acid, so wash your hands. Joel
Bartsch told this story: Specimen collecting was legal but controlled in the Tsumeb mine in
Namibia, Africa. It is most unusual to find such beautiful water clear cerussite and this specimen
sold for such a high price ($250,000) that a group of miners went into the mine on their off shift
to see if there were any more specimens. This was an uncontrolled visit and the group apparently
did not follow some safety precautions because more than a dozen men were killed in a cave in.
Page 5 of 8

Cerrusite from Kombat mine, Namibia
Just when you think it’s safe…. It is not a surprise that lead minerals are poisonous but even
quartz can be dangerous and not just by dropping a big hunk of it on your toe. Quartz is silicon
dioxide (Case 68) and Galveston beach sand is full of it and there are no warning signs. You
could eat sand and it is so inert that it would not do much to you but if you ground it up to a fine
powder and breathe it, you could get silicosis. Miners in “the bad old days” (and, sadly, still in
some places today) frequently had lungs so scarred that they had to live permanently on oxygen
or die.
Page 6 of 8

Minerals that are good for you: Yes, there are minerals that are good for you or at least not
bad.. Fluorite is calcium fluoride: fluorine is so reactive that you can “burn” a quartz rod in it but
fluorite is safe. You could grind up fluorite and sprinkle it on your cornflakes and it will do you
no harm because the compound is so stable. The collection is rich in clear, pink, yellow, blue and
green fluorite. The fishtail twin calcite (Case 8) would actually benefit you if you ate it because it
is just calcium carbonate.
So, if you have a mineral collection, wash your hands and get an expert to tell you about them.
Page 7 of 8

Photographs were taken in the Houston Museum of Natural Science Mineral Hall by the author,
Lewis Hall or from Masterpieces of the Mineral World, 2004 by W. Wilson, J. Bartsch and M.
Mauthner (with permission by J. Bartsch).
You may not find these minerals in the hall as curators change the displays frequently
Page 8 of 8