Groutite is a rare manganese oxide. Lustrous needles of groutite, to 4 mm, are richly scattered on both sides of the ribbed, quartz-replaced petrified wood. This specimen is from a remarkable and so far unique find in 1975. A miner who'd worked in the area for years brought in a small lot of specimens to a rock shop owned by Lolette Dalbeck in Ridgecrest, California. Ex. Mullane Collection.