Phillipsite is a rather rare zeolite mineral, a compound silicate forming clusters of spherical aggregates with a silky to sub-crystalline surface, ranging in color from bright white to orange red. Like most zeolites it is found in the vesicles or cavities of mafic volcanic rocks. More rarely it is known to occur as an encrustation precipitating near hot springs. This sample is from San Margarita, Ronca in Northern Italy. Actual width is 120 mm.