Used to be another spot out somewhere west or NW of Vegas back in the late 60's that was good for chalcedney roses, but can't remember where. The only time I went was with a lady from the rock club and we ran into US Army tanks on training manuevers and go out of there pretty quick. Those roses are found upside down and are real pretty.
Another simular thing are the tufa 'mushrooms" found up around Pyrmid Lake in northern NV. They used to use that stuff for gravel on the roads up there, talk about driving on razor blades, we had 5 flats in about 4 hours heading from Gerlach north.