||Spinel (octahedron on Spinel law twins)
Yen Bai Province, Vietnam
6.8 x 6 x 2.6 CM (cabinet)
A purplish-red large Spinel twin over 5 cm across is the base for a smaller octahedron and some additional crystals. Shows typical etched surfaces and has some very glassy faces. An attractive display piece that is also quite instructive, it presents the twinning in a textbook form with a non twinned example as a contrast.