Uvarovite in Prehnite from Pangasinan Province, Philippines
Uvarovite, Ca3Cr2(SiO4)3, is the rarest of the commonly encountered garnet species, and the only one that is consistently green. Although seldom faceted due to its tendency to be opaque, drusy coatings of tiny bright green uvarovite crystals on chromite matrix from Russia are used for jewelry. Recently, a new type of rock with lapidary potential was reportedly discovered in the Philippines, consisting of a white prehnite matrix with vibrant green crystals of uvarovite (see above).
This new material was brought to the authors’ attention by Xavier A. Cortez, who operates Crystal Age, a gem shop in Quezon City. While attempting to source jade for his shop in early 2019, Xavier was offered unidentified white stones speckled with bright green crystals from local miners on the island of Luzon. Mr. Cortez was able to track down the source of this material to a rural portion of Pangasinan Province, in the Ilocos region of Luzon. Weathered calc-silicate rocks at this deposit yield small euhedral crystals of opaque bright green garnets as well as compact green masses in white matrix. The measured spot refractive index of 1.63 was consistent with prehnite. The identities of the green uvarovite and the white prehnite matrix were confirmed with Raman spectrometry.
While there is currently very little of this material on the market, it could be used as a jadeite simulant due to its mottled white and green appearance. Aside from its potential as a jadeite simulant, it is an interesting ornamental material that can be appreciated for its own unique beauty and vibrant green color.
