Geology Word of the Week: B is for Botryoidal

A bunch of grapes which I purchased earlier today at the Woolworth's grocery store across the street.

def. Botryoidal:
Shaped like a bunch of grapes.

The word botryoidal comes from the Greek word “botrus”, which literally means a cluster or bunch of grapes. In geology the word botryoidal is often used to describe a rock texture or mineral habit (appearance).

Here are a few pictures of some botyroidal rocks and minerals:

Botryoidal chalcedony. Picture courtesy of Patrick Donohue.

Botryoidal arsenic. Picture courtesy of Patrick Donohue.

Botryoidal carbonate. Picture courtesy of Patrick Donohue.

Botryoidal vapor-phase altered rhyolite. Picture courtesy of Lockwood DeWitt.

Botryoidal ferromanganese crust dredged from the Ninetyeast Ridge, Indian Ocean, Summer 2007.

More botryoidal ferromanganese crust dredged from the Ninetyeast Ridge, Indian Ocean, Summer 2007.

Botryoidal (and purple!) carbonate from the Samail Ophiolite, Sultanate of Oman.

A geologist, a botrus, and a botryoidal rock.

***Thanks to Patrick Donohue for suggesting this week’s word and to Patrick and Lockwood DeWitt for providing pictures.***