Sierra Silver Grey Decomposed Granite A Decomposed Granite Material Central California quarry shipping bulk throughout California and in supersacks where requested. This is an outstanding decomposed granite material with a unique color and texture for decomposed granite. The very high quartz content and contrasting colors of white, silver, and grey quartz pebbles and fines in this material make it a superior ground cover material for landscapes with grey or silver grey color tones are wanted. Due to its superior characteristics, we also use this material for our Silver Bocce Ball Court Blends, for both the Dry Climate and Wet Climate mixtures. Even by itself it makes a great less expensive alternative to crush oyster shell mixes for Bocce Ball and Petangue court surfaces.