It’s a filament, similar to those used in light bulbs and vacuum tubes. Its purpose is to heat a a material to give off electrons. The magnetron tubes themselves are very difficult to get open. You’d do far better breaking open a few light bulbs, quite honestly, although forming the metal into a useful shape is problematic.
Thin tungsten rods are readily available at a welding supply house. They are used as the elctrode GTAW welding. You can get them in diameters up to 1/4" Note that most contain an alloy element and one of the most common is thorium which is mildly radioactive. It isn’t a real hazard apart from breathing dust while griding the tip. You can get pure tungsten electrodes but they are less commonly used so you may have to order them.
I had a piece of tungsten half an inch thick and 4 by 6 inches in area. This damn thing was almost impossible to pick up off a table top. Carrying it gives you the uncanniest feeling that there’s a spring attached to it somewhere, pulling it down. Really a remarkable sensation.
It would be very difficult to melt tungsten considering that its melting point is 3,410° Celsius (6,170° F)
Napier mentioned that it has a high density. As a matter of fact its specific gravity is 19.30 which is very close to gold’s density of 19.32. Hey, I wonder if someone tried to gold plate or even put a veneer of gold on top of tungsten, if they could … er never mind.
I was merely thinking in my limited Archimedian mentality.
I failed to think of the more sophisticated analytical test of which you speak. (Yes gold is much more maleable than tungsten isn’t it?)
Incidentally, tungsten was discovered in 1783 and so if it were to be used for “couterfeiting” gold, it would be a fairly recent phenomenon.
Now I’m getting kind of interested in getting a chunk of tungsten myself. That tungsten slab that Napier mentioned (½" by 4" by 6") would have weighed about 8.3 pounds. (If I did my calculations correctly). If nothing else, something like that would make an interesting paperweight. I’m wondering if the cost of something like that would be somewhat prohibitive.