The Geology of Inyo
The geology of Inyo is well known. Alan Gillespie wrote his doctoral thesis of the Owens Valley, home of Inyo. He relates relevent data in his article (available here). Inyo exists on a finger of the Inyo Mountains that was once shoreline to the ancient Owens Lake. It is wave scoured dolomitic marble. The exposure to the elements has made the white marble discolor. When pecked, it reveals the brilliant stone beneath.
A flash flood recently washed a portion of the older stone clean of debris that had accumulated over the past few thousand years. We searched the cleaned section thoroughly for any evidence of pecking or modifacation by ancient man. We found none.
This author has come to the recent opinion that exposed dolomite does not patinate in the normal sense of the word. Dolomite is marble and marble is reactive to acids. What I was exploring as patina was, in reality, a surface washed with acid and impurities. The source of the acid rain was probably volcanic. Where, when and which one(s) is still under question. Regardless, the acid permiated the outer layers, dissolving the softer stone enroute. The granular surface is made up of crystals of harder to dissolve material. The discoloration, white to beige, may stem from impurities carried along with the acid rain. Some experimental archaeology will have to be conducted to determine the processes.