Louise queries Rodonite…
I think that almost certainly what your friends have found is
Rhodonite, a pale to rich reddish pink massive form of Manganese
Silicate often with black spots or black marbling effects… Hardness
about 6-6.5 and used by the rock-hound fraternity as a semi-precious
gem stone.
Some of this material in my experience does not polish well because
of the variation in hardness in the black areas. Also it has been
found that exposure to sunlight will fade the colours on some of the
material.
It certainly is an unusual colour and I think that the best I have
seen was called ‘Imperial Rhodonite’, I don’t remember its source but
it was a very rich colour with virtually no black marking at all.
There is another similar material called Rhodolite, this is more
commonly in crystal form and a lovely rose pink to reddish colours
and a more expensive item than rhodonite.
Hope this helps
Keith Torckler, Cornwallis, New Zealand