Nice contrast between the green moss colonizing the vein rock and the earthy tones of the quartz crystals. A lot of the latter's coloration is surface staining with iron oxides/hydroxides and manganese oxides. I've learned that much of the staining can be removed by boiling samples (in Pyrex, not metal!) in oxalic acid. But there are still some impurities in the interior, which gives the quartz nice red, yellow and orange tones, and sometimes even amethyst-like purples from the manganese.