Greigite: a true intermediate on the polysulfide pathway to pyrite

Table 2 Induction time and total reaction times, and final solid products of the hydrothermal transformation of mackinawite to pyrite ^a).

Temperature	Induction Times (min) ^b)			Reaction Time (min)	Products (ED-XRD)
	t^-_{0 mack}	t⁺_{0 grei}	t⁺_{0 pyr}
200°C ^c)	0	8	0	90	Pyrite
200°C ^c)	0	4	0	70	Pyrite, Greigite
175°C	7	n.a.^d)	6	60	Pyrite, Greigite
150°C	4	6	12	74	Pyrite, Greigite
125°C	25 (± 3)	n.a.	22	110	Pyrite
100°C	77 (± 19)	n.a.	117 (± 30)	311 ^e)	Mackinawite, Pyrite

a) All experiments: 1.25 ± 0.13 mmol FeS and 1.25 ± 0.13 mmol zerovalent S as polysulfide.
b) Mean errors in induction times, unless stated otherwise: ± 1. t^-_{0 mack}: induction time for mackinawite decay; t⁺_{0 grei}, t⁺_{0 pyr}: induction time for greigite and pyrite growth, respectively.
c) The reaction at 200°C was conducted in duplicate.
d) n.a.: not available.
e) Reaction was interrupted before completion.

ISSN: 1467-4866