This is a rare copper-vanadium oxide and represents one of just a handful of mineral species that contain the element vanadium as a primary constituent. Neon green, highly lustrous, crystals of volborthite, to .6 cm across, are nestled in a vug in the matrix. Named in 1837 after Alexander von Volborth (1800-1876), russian paleontologist. This is one of the finest specimens I have ever seen of the mineral, which is usually just a boring microcrystallized crust underneath better copper minerals. The crystals here are sharply formed, and well-protected all these years. I believe this to be a rather significant specimen. 4.3 x 3.2 x 3.1 cm