Cassiterite, Topaz from YinDu, ChiFeng, Inner mongolia, China. Silk luster and sharp black cassiterite crystals asssociated with some small sharp transparent till translucent topaz crystals on the mica matrix. Special founds for such specie from this location. size:9.5×5.5×2.5cm, biggest topaz 1.2cm, biggest cassiterite wide 1.5cm, NO.20230129CT70.