I have a specimen my husband got from a rummage sale when he was younger that we cannot seem to identify.
We do know it is heavy(4-5 pounds approximately) and very hard(scratch test scraped off rose quartz and chipped a knife blade) It is very slightly magnetic on the sides and VERY magnetic on the top where it is dull, the sides and bottom have not tarnished over time. Let me know if there is any other information you need to help identify.
this is the top of it which is very magnetic(rare earth magnet sticks very well to the top ONLY)
the sides and bottom where it is still shiny is only slightly magnetic