Calcite. That’s what I think most of it is. I’ve
pulverised what I thought was the gypsum and although
it breaks into nice crystals that you can crush with
your teeth (so it’s not quartz), I still don’t
think it’s soft enough. Any geology textbook will
tell you that the hardness of minerals is given by the
Mohs scale, ranging from the softest, talc, to the hardest,
diamond. Now gypsum is the next softest, and typically
lets you scratch the crystal faces with a fingernail.
Next in the scale is calcite, or calcium carbonate,
which you can scratch with a knife. The crystals I had
didn’t seem to scratch easily and a quick dash
of hydrochloric acid confirmed my fears. The frenzied
fizzing of the crystals in the acid indicated that there
was calcium carbonate in there. It wasn’t that
surprising, since the veins were in limestone. What
it looked like was we’d collected a mixture of
gypsum (calcium sulphate) and calcite (calcium carbonate),
and stupidly I’d lumped everything together and
bashed it all to a powder. Kate looked about as crushed
as the powder – not a good day for geology on
Rough Science 4.
I moped around a lot.
Brainwave - Mike suggested converting the calcium carbonate
back into calcium sulphate by using sulphuric acid from
the numerous car batteries littering the yard. Great
Started draining batteries, still moping.
Pretended to be a chemist (even got the white coat
on) to mix the sulphuric acid with the gypsum/calcite
mix. Hopefully what is gypsum will stay there while
what is calcite will convert. By early evening I had
a tablespoon of white powder. Not drugs to keep me going
– gypsum residue. It was going to be a late night.
Moped a bit more.