This mineral species was first identified in Bergen Hill, New Jersey (USA). Stevensite is a rare phyllosilicate of the smectite group, with the formula (Ca,Na)xMg₃-x(Si₄O₁₀)(OH)₂. With black todorokite. This is an early specimen from Långban, Sweden. A systematic curiosity acquired from Shannon by E. Nicolau (Barcelona). u543s

Reserved

Old specimen of piemontite from this Swedish classic locality, little represented in collections. They are small burgundy red crystals on a matrix with calcite (fluorescent under SW.-UV). It is accompanied by a label of Lazard Cahn (1865-1940), a renowned American mineralogist about whom you can see more information at this link: Memorial of Lazard Cahn, Amer. Mineralogist Vol. 26, pages 174-177, 1941.

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