flos ferri
(ˈflɒs ˈfɛrɪ) n (Geological Science) a variety of aragonite that is deposited from hot springs in the form of a white branching mass
[C18: from New Latin, literally: flower of iron]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014