Ed
In Dundas, Tasmania, there seems to be remarkably extensive Cr mobility
from the original chromite (in serpentines) into stichtite (Mg-Cr
carbonate) veins (+/- Cr-chlorites, magnetites, etc) and fuchsite along
fault contacts, during metamorphism. Then, during weathering, much of
this Cr was remobilised into the groundwaters and locally deposits in
quite large masses of crocoite (lead chromate) and other secondary Cr
(III and IV) minerals.
regards
Ralph Bottrill
Mineral Resources Tasmania
03 6233 8359
-----Original Message-----
From: Metamorphic Studies Group [mailto:[log in to unmask]]
On Behalf Of Eric J Essene 1
Sent: Tuesday, 23 January 2007 08:15
To: [log in to unmask]
Subject: chromium mobility?
Ed,
One sometimes sees violet "kammererite" (chromian chlorite)
flakes in country rocks near serpentinites, suggesting the mobility
of Cr during serpentinization over scales of 10's of meters. The
"fuchsite" (chromian muscovite) that is seen commonly in Archean
metasediments probably forms primarily from nearby detrital chromite,
but also indicates some mobility of Cr.
eric
On Jan 22, 2007, at 2:27 PM, Edward Grew wrote:
> Chromium is normally considered immobile in metamorphic
> environments. Has Cr mobility
> been reported in either natural or experimental systems?
>
> Thanks!
>
> Ed
>
>
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