Two fibrous iron sulphides and valleriite from Cyprus with new data on valleriite.

• Main Authors: Harris, D.C., Vaughan, David
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1972
• Subjects: muskox
• Online Access: https://research.manchester.ac.uk/en/publications/c474f156-3f8c-4a08-b659-8ed187df470d; http://www.minsocam.org/ammin/am57/am57_1037.pdf

Two fibrous iron sulfide minerals, with optical and physical properties similar to valleriite, are described from an ultrabasic complex located near Pefkos, Cyprus. The two minerals, designated in this paper as Type I and Type II, occur as fine-grained aggregates and/or veinlets of fibrous crystals surrounding troilite. Electron microprobe analyses of the Type I phase suggest a formula 2FeS-0.84 (CaCO3·H2O). The mineral readily effervesces in dilute hydrochloric acid releasing an odour of H2S. Infrared and DTA studies show the presence of bonded H2O. The powder pattern, indexed on a hexagonal cell, gave dimensions a = 3.83, c = 33.12 Å. Electron microprobe analyses of the Type II phase suggest a formula 2FeS- 1.58(Mg0.53KiFe0.47(OH)2). The mineral does not effervesce in hydrochloric acid. The powder pattern resembles but is distinct from that of valleriite and of the Type I phase and can be indexed on a hexagonal cell with a = 3.74, c = 32.63 A. The mineral has also been identified in a specimen of troilite from the “del Norte Co.” locality in California. This phase appears to be similar to the “fibrous iron sulfide,” previously described from the Muskox Intrusion, N.W.T. and from the Lizard ultramafics in Cornwall, England. Where sufficient material was available, infrared and Mossbauer spectra of the two phases have been examined and compared to those of normal valleriite from Sweden. As they are clearly members of a group of minerals which includes valleriite, the problem of their nomenclature and classification is also discussed.