I just received my response from the US Forest Service Wood Products Lab.  They report that the specimen I sent is Anadenanthera sp.
Here’s the wood database write up of it: 
https://www.wood-database.com/curupay/
Apparently one of the common names of this is curupay, also known as Patagonian rosewood.  Too bad I didn’t get any of the foliage or bark with it, as it is an hallucinogenic, used by shamans!  So, yes, a rosewood, but only by common name - not Brazilian rosewood.  In any case, it is attractive and very heavy.  I’m looking forward to finding uses for it.