Simply the mention of Prenteg conjures thoughts of the three titanium dioxide polymorphs and this terrific miniature is a rich example of Brookite richly scattered over a bed of glassy micro-crystals of Albite with Quartz. The actual locality is Twll Maen Grisial, a little to the southwest of Prenteg, the type locality for Brookite which holds an iconic status in British mineralogy. Over twenty semi-transparent golden bronze Brookite crystals of up to about 1 mm occur on the Albite and sparkle brightly when the specimen is rotated.
Comments