Thompson's water seal cleaner has oxalic acid, just make sure you read the back and it will have a warning saying it has oxalic acid in it. Just make sure you:
1) use rubber gloves
2) mix the acid in water, not water into acid. If you use Thompson's, use the full gallon (about $15) and if you want to dilute it a little, add no more than 1 gallon first, then dump in the Thompson's. I've used it before and it works great.
3) get an el-cheapo hard wire brush, they cost like $2. The wire isn't nearly hard enough to scratch quartz.
You can keep re-using that stuff for a long time as long as you clean and dry your specimens before dunking them so you don't affect the Ph any more than you have to. One batch would clean at least dozen or more rocks the size of a cantaloupe.
Start with hot water from the tap, it will cool down but just don't let it get cold (like below 50 F or so) or it will lose it's efficacy. It will take at least a day or two to eat off the stuff or loosen it up, so don't get discouraged even if it takes the better part of a week. It works great against any organic matter like algae and tannin and also takes off iron staining.
A cheaper and better way is to just get raw oxalic acid, but it is not likely to be readily available nearby, you'll have to order it off eBay or something. I got 2lbs of it for $15 off eBay and that will do about 12-15 gallons or so.
So I just found this at the beach and it's covered in algae I believe it's agate and it definitely sparkles already after just some warm water, any suggestions??
