Currently on holiday in Scotland & wanted to have a hunt for some Scottish Gold. Using an SDC2300 these rocks give a signal like a rusty horse shoe - very loud. No rusty colour to the rock though to suggest ironstone. If anything it resembles blue stone. Also a lot of blackish/grey sand at edge of river at eddies, which also gives off strong signal with SDC. Didn't find any nuggets (yet), but found this 1921 George V Florin, which I was absolutely rapt with. Took about 20 minutes to dig out to, it was quite far down.