"The specimen was not of urinary origin." With those simple words our mineralogical reports summarized some strange things. You never knew what you would find when you opened the little yellow pill box most stones were submitted in -- ranging from gold to dead flies and rocks of diverse sorts. We learned that sometimes such findings were offered by patients in order to get drugs, such as the case of the specimen that was a half-inch chunk of cement block, complete with silver paint on one side. We thought that the silver paint seemed rather industrial or institutional, and indeed the doctor wrote back to say that the patient was from a prison.
We never did find out where the gold came from, but there it was, seven little nuggets of soft, porous gold. We presumed it was dental gold, and it was so little that it was not worth even $5, but it was quite a shock to discover it!
The first non-urinary stone arrived while I was still a geology grad student at Indiana University. A quarter-inch long, non-descript, rounded brown pebble-like stone defied identification until it was submitted to x-ray diffraction analysis. This technique reveals crystal structures, which are nearly unique patterns that are characteristic of each mineral, no matter what its origin. The analysis was clear: We had a piece of gehlenite. What is gehlenite? None of my geological colleagues knew either, but the mineralogy texts quickly showed it to be a high-temperature (we're talking hundreds of degrees!) metamorphic mineral, an iron silicate, common in slag piles of steel mills. Sure enough, the specimen had come from a doctor in Cleveland, Ohio, part of the steel belt. We never got any further information about that one, but it may have been a simple mistake in collecting a relatively tiny specimen.