Tsaregorodtsevite is a very STRANGE mineral that is made up of AMMONIA with nitrogen, and an aluminosilicate compound. I recall when Fersman Museum started selling their extras in 1991, this was one of the most coveted of all rare species that came out the doors from their various expeditions. I got some directly at the time from curator Dmitriy Belakovskiy, who has himself been to this remote location on at least one expedition. I assume this specimen came form the same source, the only source so far as I know. I have owned several over the years, and I can say this is a very good and rich specimen. It has crystals to 4mm.