Mineral: Opal-CT var. Tripoli
Locality: near Virginia City, Storey County, Nevada
Description: Lightweight mass of Tripoli, a variety of Opal-CT, also known as infusorial earth prior to 1892. Ex. James Underhill collection #96; ex. A.E. Foote (1846-1895)
Overall Size: 7x6x3.5 cm