This Datolite nodule has a rare blue/green coloration due to the alteration of included specks of Copper. This mine is noted for Datolites of this color the vast majority of which were found in 1962 from the 48th level south. The exterior has a rugged, knobby texture which is similar to others from the 1962 find. The polished surface is dull unlike Datolites from other location in the Michigan's copper mining region which is likely due to the altered Copper inclusions.
Flaws: There is a hairline crack and a chipped area along the edge which is visible at the bottom of the second picture.
This mineral is also found in the following galleries: Minerals From Michigan | Nesosilicates | Copper | Minerals with Inclusions | Polished & Worked | Minerals Priced Between 300 and 499 Dollars