[Richard Farrant]

It sounds like this casting is of magnesium content. The guy in the workshop next to me was salvaging parts from a Ferguson TE20 gearbox and said that when he used a disc cutter to split the box (don't ask), it was like fireworks. I told him the casting were Elektron, which is a magnesium alloy. It was first used in the 1930's in the UK, a German development but a company in UK was producing it. The gun mantlet on the late 30's Vickers Light Tank Mk6a was Elektron and when one was being restored over here, I was doing some work on it and the welder fabricator had to build up corroded areas of it. This he done with TIG and used an Elektron rocker cover from a racing car to cut up and weld in, finished job was very good, but he said he had to do it in small bits in order not to have it catch alight. An old neighbour of mine worked for Dunlop during the war, machining aircraft wheels, he said you learnt quickly on not to take large cuts on the lathe otherwise the swarf would catch alight and cleaning up a lathe after it has been covered with sand is something you did not want to repeat.
Electron is lighter than aluminium but also stronger.

regards, Richard