TF90Z8: Aggregate of very sharp dipyramidal crystals with the dipyramid truncated by the pinacoid. They are large for the species (and very large for the locality) and are translucent, bright and have a very deep greenish-blue color, but it varies depending of the kind of incident light, more blue in daylight. A thumbnail of high quality.
Ojuela Mine, Mapimí, Municipio Mapimí, Durango  Mexico (08/2013)

Specimen size: 2.7 × 2 × 1,3 cm = 1.06” × 0.79” × 0.39”

Main crystal size: 1.2 × 1 cm = 0.47” × 0.39”