Certainly the discussion has not degenerated into a name calling squabble, but just to prove I'm not simply talking out of my a$$ (that would be an interesting ventriloquist act!), here are a couple of screen captures from Trek Core that reveal Vaal is being "fed" the chemically unstable mineral shards.
In this first example, one can see the hands of a woman on the far right (plus the tip of her left boob) holding a sizeable rock.
In the second, wider shot, we can see on the far right a young female bending to grasp a rock from a neatly stacked pile. Towards the left of the shot, we can see a male at the front of the line with a fair sized rock, a woman behind him with a much smaller rock, and a male behind her carrying, well, the hint of green could make one reasonably assume it might be something organic with chlorophyl.
As an unrelated bonus, here are two captures of the yeoman going all "Emma Peel" on a native. Too bad there isn't a shot of the actual flip, but you gotta' love the "after" stance! Meow!