Breyite

Breyite is a high pressure calcium silicate mineral (CaSiO₃) found in diamond inclusions.^[3][4] It is the second most abundant inclusion after ferropericlase, for diamonds with a deep Earth origin.^[5][4] Its occurrence can also indicate the host diamond's super-deep origin. This mineral is named after German mineralogist, petrologist and geochemist Gerhard P. Brey.

CaSiO₃ phase diagram showing Breyite is stable around 3-9 GPa^[6]

Breyite
General
Category	Minerals
Formula	Ca3.01(2)Si2.98(2)O9
IMA symbol	Byi[1]
Crystal system	Triclinic
Space group	P1
Unit cell	a0 = 6.6970(4) Å, b0= 9.2986(7) Å, c0 = 6.6501(4) Å, α = 83.458(6)°, β = 76.226(6)°, γ = 69.581(7)°
Identification
Colour	colorless
Cleavage	not observed
Luster	vitreous
Density	3.072 g/cm3
Ultraviolet fluorescence	non-fluorescent
References	[2]