 It has also been reported from the Osborn District in the Big Horn Mountains of Maricopa County, Arizona and the Lavrion District Mines of Attica, Greece.Herbertsmithite has a vitreous luster and is fairly transparent with a light-green to blue green color.Herbertsmithite has a Mohs hardness of between 3 and 3.5 and is known to have a brittle tenacity.