Cassiterite and Quartz   Dayu,  Jiang Xi Prov., China.    7 x 5 cm plate of transparent casssiterites that are up to 2 cm across each.  Even brown color, high luster and great form make these exceptional crystal.  The gemmyness of these crystals is difficult to evaluate from my photos because I don't backlight, but it is certainly exceptional.   250$