Specimen data for Ushkovite

Tom Mortimer catalog number: U952

Identification method: Via personal communication from Bob Janules: "The late Larry Pitman, while working at Harvard, confirmed" (Charles Davis ushkovite) "by optics. The identification was further corroborated by SEM analysis"
Pitman stated: "The yellow phosphate, from specimen 1-C-2 [Charles Davis specimen], is, from optics and specific gravity (2.36), certainly ushkovite. ...The foliation observed looking down 2 appears exactly like that in Mineral Encyclopedia Vol II ....I made a Gladstone-Dale calculation on the above crystal, using the observed specific gravity and average refractive index against the chemical formula for ideal ushkovite. The result was superior (0.007) using Mandarino's criteria and suggests that the material is close to the ideal formula."

Notes: Ushkovite is frequently confused with the more common species laueite. Association with scorzalite, also an iron-magnesium phosphate, increases the likelyhood of ushkovite.