pleochroic halos

pleochroic halos

[¦plē·ə¦krō·ik ′hā·lōz]
(optics)
Halos of color or color differences that are sometimes observed around inclusions in minerals, resulting from irradiation by alpha particles.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.