I have an inherited collection and in it I have a few stumpers. I have been to shows, and clubs.. and yup, no clue. I have a few bits of what everyone has agreed is quartz, but where and when is unknown (I ended up with a collection that was left in a storage shed for like 30 years, prior to that long absence, someone had lovingly collected about 40-50 tonnes of stones. Some of it is inexplicable, I don't know what he was keeping it for... Other pieces have proven he had an amazing eye for stones, no skill whatsoever at making Cabs though ::shakes head::
I have not slabbed any of what everyone has called Tangerine quartz, it is literally the bright almost false colour of tangerine juice. I have a cruddy saw still so not a lot of slab work thus far, I am still shaping down the ::thinks:: 90 boxes of slabs that were in the collection, including one mostrosity that appears to have been cut on a 40+" blade.. maybe a water jet or a very large band saw, the face is a good meter tall, and about 30cm across... I have not even seen a saw that would pass this beast.. and like i said.. there is just nothing there of interest. It is a mottled red/brown jaspar that aside from the size. is totally unremarkable.
If you want I can dig into the cratres this week and get some pics for ya.