Black granite is usually diorite (black with white), diabase or gabbro (often totally black) and not granite, and while there black flakes in ordinary granite which are biotite mica, many of the black crystals are schorl (black tourmaline), the black color of gabbro is mostly hornblende. You'll also find gneisses and migmitites, which are granites to gabbros that have been partially melted and may have separated into layers through partial recrystalization, and often show signs of being squeezed into folds like toothpaste.

Jade of the nephrite variety is a massive agglomeration of small interlocking, intergrown actinolite crystals. Jadite is made of interlocking fiberous crystals that cling together so well the bulk material is stronger than steel.