Palagonite

The name palagonite was applied by S. von Waltershausen in 1845 to a resinous yellow-brown material, thought to be a new mineral species, occurring in tuff at Palagonia, Silicy. Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt. It forms by the low-temperature hydration of the clear basaltic glass (called sideromelane by von Waltershausen in 1853) found in hyaloclastites, tuffs, and pillow lavas, which results particularly from the quenching of basaltic magma in water. Volcaniclastic rocks rich in palagonite are widely known as palagonite tuffs or palagonite breccias. Quaternary volcanic assemblages in Iceland consisting largely of such rocks were once called the "Palagonite Formation".

Pillow basalts surrounded by yellow palagonite. Columbia Plateau, USA. Image from Geotripper.

Pillow basalts surrounded by yellow palagonite. Columbia River Basalt, USA. Image from Ice Age Floods.

Pillow basalts surrounded by yellow palagonite. Columbia River Basalt, USA. Image from Ice Age Floods.

Pillow basalts surrounded by yellow palagonite. Columbia River Basalt, USA. Image from Ice Age Floods.

Bibliography

• Allophane and palagonite: similar neoformation at low temperature. M. GERARD and G. STOOPS
• Gerard, M., & Stoops, G. (2005). Allophane and palagonite: Similar neoformation at low temperature. European Geophysical Union Geophysical Research Abstracts, 7, 09053.
• Peacock, M. A., & Fuller, R. E. (1928). Chlorophaeite, sideromelane and palagonite from the Columbia River Plateau. American Mineralogist: Journal of Earth and Planetary Materials, 13(7), 360-383.

Photo
Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)
Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. XPL image, 10x (Field of view = 2mm)
Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)
Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)	Palagonite (green) filling an amygdale. PPL image, 10x (Field of view = 2mm)