Mendip Potato Stone (aka Dulcote Agate)?

There is a mindat person who owns the field where Mendip Potato Stone (Dulcote, Somerset, UK) is found. I'm wondering if he can help ID this? I have other Dulcote Agates that look like geodes from the same collection. This looks similar, bit isn't a geode. Can anyone help here?



Amanda

I'm also wondering what the yellow-ish botryoidal mineral is in the photo below - (a part of the same rock)?



Amanda

Hi Amanda

Patatoes stone, wouldn't like to have these on my stomach, a little to heavy to digest ( lol )
The botryoidal mass is probably chalcedony or agate, but as agate is a variety of chacedony what is on his turn a variety of quartz.
Just keep the chalcedony, no harm with that.

I hope this helps.

Take care and best regards.

Paul.

Hi Amanda, I have plenty of these myself, and some of them are very pretty inside, and some of them are geodes, yours seems to be just another type of chalcedony (crypto-crystalline quartz) mixed with a little jasper, calcite and other earthy material!

Spencer.

The owner of the field where they come from has confirmed it is not a Potato Stone. Has anyone else any ideas where it may have originated, possibly in the UK?

Thanks!

Amanda

Spencer, I have this part Geode with quartz crystals inside - is this a Potato Stone?

Amanda

Hi Amanda - yep, its usually the hollow geodes that are referred to as the 'potato stones' (your crystal lined partial geode) or Dulcote Agate stones.
your first stone could well be from in or around the same area and still looks to be cryptocrystalline Quartz - just more likely not hollow .
These stones are from the Mercia Mudstone Formation, Mendips, Somerset, England. Potato stones are anhydrite (hydrated gypsum) nodules which have been replaced by quartz and calcite.

Hopefully thats a bit clearer!

cheers, Colleen

Thanks Colleen! That's very helpful

Amanda

Amanda - that is a potatoe stone. Well done on finding it! I cave on the Mendips and teach climbing and caving there, they are becoming hard to find these days! Nice one you have as well

Amanda although the area ime excavating in the southwest of Cleveland is above mercia bedrock ime no expert as i believe not many are as so lttle is known ofthis period due to the conditions, but the outer skin apearse to be covered in a fossil matearial?

Hi Amanda
Again your not quite there the quartz lined geode that you have pictured is I believe is of Moroccan origins it's not a potato stone the exterior is wrong ald also the rind has a reddish band very common with Moroccan agates
Hope this helps you
Mike