Inside the flint, where its very black i would maybe add some more highlights because it blends way to much with the black background. And, at first glance i thought it looked like a sea shell, maybe smooth out the edges in some areas too give it a smooth rocky look to it.

@The_Silent
Are you planning to make edits for this and other ones in awaiting update?

This icon has no moderation? For the rest? No idea. Feel free to move them to rejected, pretty sure updates move them back in the queue again anyway.

Okay.
Regarding this one, for better review you'd have to give bigger version because it is uneasy to see how much definition is put and would zooming in be of any help. For more realism I'd get rid of thick while lines. At the moment, in this spider web shape going across the whole object, they don't give much of idea what material this is. There should be more color values, if not different colors as well. Lightsource needs to be defined. Check some vanilla icons of stones and crystals for shape. Try to make it more polished.

Although lacks of some polishing, it can be easily recognized as a stonnish object.
Approved as author is not willing to update it.

Submissions must also have a bordered 64x64 BTN image of the icon as the preview. Fixed.