Natural moissanite (SiC) – a low temperature mineral formed from highly fractionated ultra-reducing COH-fluids

Table 1 Experimental phase compositions and calculated oxygen fugacity

	P [GPa]	T [°C]	t [h]	X _Mg ^olivine	X _Mg ^opx	Metal or silicide [wt%]					$Δ log f_{O 2}^{I W}$ SiC-C-ol-opx
						Fe	Ni	Si	Ir
G#1	2	1300	48	---*	0.982(5)	8.1(26)	0.24(9)	59.4(43)	20.3(20)	+quartz	---
G#2	2	1500	15	0.997(1)	0.998(1)	77.4(13)	3.3(4)	18.0(4)	---	Fe₂Si	-6.4
G#3	10	1500	72	---*	0.995(1)	60.3(10)	2.7(8)	35.0(17)	---	FeSi	(-4.9)**
						46.6(21)	0.9(5)	49.5(16)	---	FeSi₂
						30.8(6)	1.3(2)	64.4(20)	---	FeSi₄
G#6	10	1700	54	0.993(2)	0.995(1)	75.6(11)	2.6(9)	20.8(4)	---	Fe₂Si	-5.6

*Rims or silicide-free exsolution zones of previously San Carlos olivine too small to measure by EMPA.
**From equilibrium (1), the FeSi is most likely formed metastably in the early stage of the experiment.