Stannite is a rare sulfide of copper, iron and tin. It is collected mainly in not very pretty specimens, as simply a rare and desirable mineral - but on uncommon occasions, you find a specimen that is actually aesthetic as well, like this one. There is a LOT of stannite here, as well as sparing light purple fluorite. But what makes this specimen so good is that the stannite has grown towards the bottom of an elegant, translucent, complete and terminated quartz crystal.