Kaufman and Jaffe (1946) state the "lowest refractive index [of this specimen] is equal to 1.805". No other data collected. Data are in conflict with that of true cronstedtite. Heinrich (1960) merely relists the previous article. This is the only report of cronstedtite from a granite pegmatite and appears incorrect until verification can be made.
Quality of samples:
not specified / average specimens
Kauffman and Jaffe (1946): 582; Heinrich, E.Wm. (1960), AZ Bur. of Mines Bull. 167: 19.