After the isolation of working on my own in the last
programme, it was great to hear from Kate that our next
challenge would involve us working together as a team.
On the face it if there were two separate challenges
– first to build a refrigeration unit to make
a water coolant (Mike, Kathy and me), and second to
build a circulation system to pump that water round
a make-shift spacesuit (Jonathan and Ellen). Actually,
whether or not this was going to work would hinge on
the two teams designing this together. So our morning
was really about putting our heads together to see what
the options were. That’s what’s nice about
the Rough Science format – the instances of jeopardy
and the backdrop of healthy competitiveness never take
away from the fact that scientists tend to want to work
collectively on problems rather than beaver away on
their own. At the end of the day it’s a team sport.
Mind you, as a geologist I confess that I wasn’t
much help in thinking of how our system would work –
I mainly fiddled nervously with my hammer. I just couldn’t
think how my geological skills were going to help here.
As the new kid on the team, I’d also got the feeling
that our production team had fingered me for the final
test – walking in the spacesuit in the searing
temperatures of Death Valley. Perhaps that’s what
the geologist would be good for in this programme –
bait. Ellen – bless her – put a stop to
that, arguing passionately that we were all equal members
of the team and that it wasn’t fair to pick on
anyone (even a geologist). Rallying to support her,
I pointed out that the spacesuit was too big for me
anyway. Perhaps less helpfully, I pointed out that it
was perfect fit for Ellen. Clothed in bright red cotton,
I think she wished she’d kept quiet.
As the day wore on and hard graft started looming,
I finally thought of something geological I could do.
Our idea is to make a refrigeration device by creating
a partial vacuum, inside of which water will condense
into steam, cooling as it does so. Normally of course
that happens at 100C, but if we get the pressure low
enough we ought to get steam at normal air temperature.
The trouble is that the steam will condense back into
water, reversing the reaction and giving off heat. To
solve the problem, Mike has caught onto the fact that
the washing powder in our trunk contains zeolite, a
mineral substance that draws water vapour into its crystal
structure and holds it there. I had no idea that zeolite
was in washing powder, but I did know that it occurs
naturally in volcanic rocks. At last, a chance to escape
the workshop and get into the wilderness. Kate, keen
for more offroad driving, is a willing chauffer.
Now to most geologists zeolites are rather boring,
unimportant minerals – quickly passed over in
most geology lessons. But to chemists, zeolites are
amazing minerals, with hundreds of different uses. For
me, the worry is that their crystals come in lots of
shapes and forms. Often they appear as tiny glass-like
bubbles in volcanic ash (tuffs) or lava flows, but sometimes
mixing of water and heat in deposits underneath lava
flows can convert the whole deposit into a thick layer
of whitish powdered zeolite. This is a particularly
common in the desert volcanic landscapes of western
USA, so that’s the form I was hoping to find.
Finding volcanic ash layers and ancient lava flows is
no problem around our silver mine home – much
of the geology of the area is volcanic. The problem
is distinguishing our zeolite layers from common old
clay, since both have that fine whitish appearance.
Zeolite minerals tend to have a sheen that clay particles
don’t have, but the real test is to heat it up.
Zeolites adsorb (take in) water vapour without chemically
reacting with it, so later, when heated, they release
the water back again. That’s where they get their
nickname – ‘boiling stones’. Armed
with a bucket and a primus stove, Kate and I hunted
nearby volcanic rock outcrops for our powdered prey,
and until we struck lucky. A few smacks of the hammer
and a quick burst of flame and we had our frothing stew
of zeolite. Almost good enough to eat!