Alan-
Manganese and iron are in adjacent columns in the periodic table of
elements and thus have similar chemical properties (as do cobalt and
nickel, which head the columns on the other side of iron). The four
elements thus have similar, though not identical, chemical properties.
Mn, Co, and Ni always tend to be concentrated in iron ores IF these
elements are present in the magma (for igneous rocks) or in meteoric
waters (for sedimentary iron ores, and metamorphic ores derived from
them, like taconites). But Mn, Co and Ni are much less abundant in the
earth's crust than iron, and thus most iron ores do not contain
significant amounts of them. Feinan in Jordan is perhaps the best known
example of an ore district exploited in prehistory that has high-Mn
ores, as revealed by the excellent work of Hauptmann, Wesigerber and
colleagues.
There is no correlation at all between Mn content and water content,
grain size or any physical property except (sometimes) colour. Most
sedimentary ores form in oxygen-rich environments , in which the common
iron minerals are red, brown or yellow, while the major manganese oxide
minerals are black. But these color differences may not be apparent to
the unaided eye if the grains are very small. These minerals can
however be distinguished under the microscope - see Rob Ixer's online
Atlas of Opaque and Ore Minerals and their Associations
(http://www.smenet.org/opaque-ore/) for details.
Dave Killick
On May 15, 2005, at 4:08 AM, Alan Williams wrote:
> Is there any connection between the manganese content of an ore, and
> any
> other physical attribute ? e.g. water content, grain size, colour,
> which
> might them reduce faster ? Are high Mn contents ever associated with
> high P
> ?
>
>
> Alan Williams
>
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