Wherabouts did you collect them? There are some pretty good geological maps you can look at online.
Also, I've never found the vinegar test very helpful; acetic acid is really too weak to be effective. Best thing to do is test the pH (and hardness if you have a DH or GH test) of a bucket of water, dump the rocks in and test again in a couple of days and see what's happened.
Im from N.ireland, collected them from carrickfergus beach, not actually on the beach where the water would be, but near a railway line
so quite possible they havent been in touch with sea water.
I'm no rock expert but some of these samples do look like volcanic granite i've seen on Ben Nevis.
Keith.
Yea some other people are saying they look like granite. Whats Ben Nevis?
Test them all with vinegar if it dosnt fizz then it ok to use.
I would personaly be very wary of anything that came from the sea.
I know what you mean, there have been loads of successfull people who have used rocks from the beach.
