Home > American Minerals III – May 26 > MS1573 Gibbsite

Gibbsite - Sold


Gibbsite is one of several natural occurring polymorphs of aluminum hydroxide. Gibbsite forms platy crystals, typically in tight spheroidal aggregates. The mineral name honors Colonel George Gibbs (1777-1834), a mineral collector and gentleman scientist. Torrey (1822) assigned the mineral its modern name; its type locality is in Massachusetts.

This is an interesting example of gibbsite growing on stalactictic iron oxides. The locality is a former iron mine, starting operations in 1850; which stopped and resumed in 1880, but by 1900 all work had stopped (Sloto, 2009). Gibbsite flakes show their pearly luster by shimmering along the stalactities. This is historic specimen, carries labels from the Kessler and the Ralph Dietz (1912-1993) collections. Kessler's label records purchase form R.M. Wilke in 1943.