Tourmaline, Schorl cluster - Minas Gerais, Brazil (MS2902k)
Discrete Tourmaline crystals have inter-grown into a nice palm-sized specimen weighing about 100 grams and measuring about 60mm x 45 mm x 30mm. Encrusted with other minerals, such as feldspars (and Apatite?) adding contrasting color. The yellow cube is a typical bouillon cube, measuring about a half-inch on a side, photographed for size reference.