I recently started collecting corundum sapphires. Here in Brazil, as was the case in Montana in the United States a long time ago, there is exploitation of corundum for industrial purposes and also some for the production of low quality rubies.
I already posted some images in this forum about this and now I send some more, but now of another type, trapiche. They have several blue, grayish blue and even pink to red colors, all of them with trapiche, the largest weighs two kilos approximately. Are these stones very common or are they rare? Can someone help me?