Halloysite n. : A claylike mineral, occurring in soft, smooth, amorphous masses, of a whitish color.

Example:


Taxonomy
Halloysite, Clay Minerals, Clays and Clay Minerals, Occurrence, free encyclopedia, clay, Kerr, scale, minerals, spacing, decomposition, catalyst, Volume 1, aluminium, silicate minerals, tropical soils, search, TEM Image.

Defination from the web:
halloysite is due to hydrothermal alteration, and it is often found near carbonate rocks. For example, halloysite samples found in Wagon Wheel Gap, Colorado, United States are suspected to be the weathering product of rhyolite by ...