Polydymite and chrome-rich fuchsite in virginite from Baie Verte, Newfoundland
THE Baie Verte peninsula in north central New-foundland is crossed by the major NNE-trending Baie Verte fault which is associated with a series of ultramafic lenses of ophiolitic origin (Williams, 1977). A number of the smaller of these lenses occur as an attractive mott led green rock, known as vir...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.631.4915 http://www.minersoc.org/pages/Archive-MM/Volume_50/50-358-723.pdf |
| Summary: | THE Baie Verte peninsula in north central New-foundland is crossed by the major NNE-trending Baie Verte fault which is associated with a series of ultramafic lenses of ophiolitic origin (Williams, 1977). A number of the smaller of these lenses occur as an attractive mott led green rock, known as virginite, which is widely used for ornamental display. It also occurs as distinctive fragments in the Si luro-Devonian Cape St John Group volcanic rocks and sediments (Neale et al., 1975). The virginite has not been precisely described, usually being referred to as fuchsite rock (e.g. Neale et al., 1975; Williams, 1977). Therefore, samples of the rock, collected from pods in a crush zone on the complex and the intimate association of pyrite and polydymite suggests that exsolution has probably taken place. The pyrite has a much higher Co/Ni ratio (0.5-0.6) than the polydymite (0.04). The pale green colour of the breunnerite is clearly due to Fe substituting for Mg; all analyses contain more Fe than the minimum of 5 mol. percent FeCO 3 which distinguishes breunnerite from magnesite (Deer et al., 1962), but not so much Fe that the colour becomes brown. The composit ion of the fuchsite in the above two |
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