Why do all quartz crystals not grow large beautiful crystals?
it depends on what you mean. is it worth hundereds of dollars... bably not. is it set in gold? the gold will be worth something. there is a mystical value to quarts though.
To be brutally honest, no. If it's a particularly large or beautiful piece with well-formed crystals, you may be able to sell it, perhaps over the internet or maybe to a crystal shop. But I'm not sure how much it would make, you could check crystal shops in town to see what they're going for. In New Zealand it'd be under $15 NZ dollars, which isn't much really, so if it's of any importance to you because of where it came from or who gave it to you, you'd probably be best keeping it than trying to make some money. Quartz is a pretty common mineral really.
