The idea of not having aluminum in coal mines is apparently something to do with the ease with which sparks are struck off it and the temperature of such a spark (higher from alloy, apparently). Added to the possible presence of methane gas, with predictable results. Dead canaries. Gypsum,on the other hand,doesn't present the problems to the same extent, anything like. The rock is strong enough such that roof propping is largely unnecessary, and large galleries are carved out, leaving rock pillars to support the roof.You still don't want petrol engines shoving out carbon monoxide underground, though, so you use diesel engines instead,and can also store the fuel down in the pit. Makes you cough,probably,but wont kill you. Britsh Gypsum have bought Land Rovers over the years,removed the tops,and lowered them nose first down the shaft. They never come up again, and are cannibalized for spares down the pit .I asked the bloke I knew who worked there why the hell they bought hardtops. He said they had bought some soft tops,but they sold the hardtops and made a small profit??????? You tell me.
The exception to this rule is the engineers Rover,the oldest of the lot. A Series 111,it is a truck cab with the roof removed off the cab,and a flat sheet of steel put on instead. In this guise,it can just get up and down the adit, but the driving position becomes interesting. I've sat in it and promptly got a cricked neck.
The bloke I knew asked me once if I wanted any spares,to come and have a look. One of the properties of Gypsum dust is it sets rock hard,and gets everywhere. So I declined,for this reason,and because by then they were using N/A 2.5 diesels and 2.5 Turbo's. I *did* entertain the fantasy of getting a complete N/A 2.5 for mine,but having seen the state of Gypsum mining machinery before,figured it would take the rest of the century to get the bloody stuff out of the engine,so didn't bother.
*Token* Limey? Impertinent youth!Still the *only* limey,lad,he's Welsh. You know,the people we *always* beat at Rugby. Incidentally,you *do* know the origin of the term *Limey*, I suppose? Has to do with Parsimonious Admiralty. Essay in not more than ten words by a week next winter.