Realgar

Stubby prisms of a deep resinous orange, translucent at the edges, on a pale grey matrix. It is the handsomest thing in the register and it will not last, which is the standing problem with realgar: light turns it. In sunlight it goes to a yellow powder over months, and once it starts it does not stop. The specimen lives in a closed box now and the photograph on this page is the best record of it there will be.

The streak comes out orange-yellow, noticeably lighter and yellower than the crystal, sitting at 74° — the head of the yellow sector and a good forty degrees off the reds it was collected in the same afternoon as. Standing on the shingle they all read as warm lumps. On the plate they separate cleanly.

Realgar is an arsenic sulfide, and I streak it last on any given evening and wash the plate twice afterwards. The powder is not something to be casual with. That said, the danger is routinely overstated by people who have never handled it; the rule is the same rule as for anything else, which is that you do not eat it and you do not breathe it.

It came out of the same gravel as the cinnabar, six months apart, which is not a coincidence: sulfides of mercury and arsenic travel together and Sarnwell drains a body of rock that has both. The sough is the only working in the district that is still running water, and running water is what does the sorting.