Prehnite was the first mineral to be named after a person: its discoverer, Dutch Colonel Hendrik Von Prehn. Von Prehn discovered the stone in South Africa in 1774. Prehnite is...
Psilomelane describes a group of hard black manganese oxides, including Hollandite and Romanechite. Psilomelane consists of hydrous manganese oxide with variable amounts of barium and potassium. Psilomelane is erroneously, and...