Try something around 10% HCl. If you don't know someone with a pool, try
the pharmacy. Most of them can mix a dropper bottle full if they are in the
mood, or at least they used to be able to do so. Or try scratching a bunch
of the pieces of gravel with a knife blade... quartz won't scratch easily,
anything softer could cause trouble. Limestone will scratch fairly easily.

Bob

"LeighMo" wrote in message
...
it looks like smooth rounded quartz-based stuff with other stuff in it

If it's quartz, it should be okay. But some of the gravels sold for
fishtanks
are not inert. If they're meant for marine or African tanks, they can
raise
the GH quite a bit.

no
fizzing when I put it into vinegar, etc).

Vinegar probably wouldn't be strong enough to get a reaction.



Leigh

http://www.fortunecity.com/lavender/halloween/881/