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Iain's Communication Diary Day 1 2 3

Day 2

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 idea.

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.

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Iain Stewart
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