Tetragonal Almandine-Pyrope Phase, TAPP: finally a name for it, the new mineral jeffbenite

Nestola, Fabrizio; Burnham, Antony D.; Peruzzo, Luca; Tauro, Leonardo; Alvaro, Matteo; Walter, Michael J.; Gunter, Mickey; Anzolini, Chiara; Kohn, Simon C.

Tetragonal Almandine-Pyrope Phase, TAPP: finally a name for it, the new mineral jeffbenite

Date

2016-12

Authors

Nestola, Fabrizio

Burnham, Antony D.

Peruzzo, Luca

Tauro, Leonardo

Alvaro, Matteo

Walter, Michael J.

Gunter, Mickey

Anzolini, Chiara

Kohn, Simon C.

Publisher

Mineralogical Society

Abstract

Jeffbenite, ideally Mg3Al2Si3O8, previously known as tetragonal-almandine-pyrope-phase ('TAPP'), has been characterized as a new mineral from an inclusion in an alluvial diamond from São Luiz river, Juina district of Mato Grosso, Brazil. Its density is 3.576 g/cm³ and its microhardness is ∼7. Jeffbenite is uniaxial (–) with refractive indexes ω = 1.733(5) and ε = 1.721(5). The crystals are in general transparent emerald green.