I was going to start a thread for this, but I'd just as soon post them here. This is a great thread!
I go rock hounding on the beach as often as possible. (Oceanside, for those wondering where) Last week I found this big chunk of quartz, it's the largest beach agate I've found so far. The coolest part, is when you put a light behind it, it just lights up! And, there are about a half-dozen little holes going through it, where I'll put a few LED lights when I find the perfect ones to turn it into a decoration.