[meteorite-list] 'Mars' meteorite

[Bill Southern]

A simple streak test will ID either..

Magnetite - greasy black or grey streak

Hematite - Reddish to rust brown streak

On unglazed porcelain.

Bill

--- Elton Jones <jonee at epix.net> wrote:

> Gary K. Foote wrote:
> 
> > It looks more like a huge hematite node.  Even its
> crumbs are magnetic.  Pieces from it are flakes,
> rather than 'chunks'.
> >  
> >
> Hello Gary,
> 
> I respect that you took the time to actually go see
> this over-hyped 
> paperweight . This is clearly a rock of igneous
> origin with minor 
> metamorphism possible. However the likely magnetic
> component is 
> magnetite for the following reasons.
> 
> While it is hard to do good ids from photos,
> Probability-wise  this is 
> from a pegmatite which could be local or glacially
> transported in the 
> same vein(pun intended) as the deposits of Balmat
> New York or St 
> Lawrence County or even Quebec Canada.  The mass
> looks like a classic 
> actinolite-tremolite-pyroxene group composition
> along with about 15-20 
> other minerals.  The three which are likely the
> cause of the magnetic 
> attraction are Chromite(>2% chance) or Magnetite
> (>90%chance) and 
> secondary hematite (>5%chance).  If there is a talc
> trend (aka 
> soapstone, greesy feel) or any iron sulfates (
> brass-colored, metallic 
> flashes aka Pyrite Group) this indicates the mass
> had some hydrothermal 
> alteration and hematite could be present. In a non
> perfect world, I know 
> there is some hematite in the mass-the law of
> probability says so but on 
> the order of less than .001%. The law of probability
> also says the 
> magnetic attraction is due to magnetite in micro
> crystals within the 
> mass. Hematite is usually associated with
> sedimentary deposits but can 
> be found natively in metamorphic and igneous rocks.
> 
> Actually the composition of this mass has a lot in
> common with minerals 
> found in meteorites save for the hydrated silicates.
>  The holes are 
> likely from areas that were more hydrated and thus
> softer than the  
> original pegmatite and therefore were gouged out
> during rough ice or 
> stream transport--(if not actually human made).
> 
> There is a long history of mining the magnetite
> deposits of New England, 
> while else where in on the east coast the desposit
> of iron are in the 
> from  hematite and limonite(bog iron).  Be it noted
> that hematite is no 
> always magnetically attracted.
> 
>  In addition to magnetite, which can be truly
> magnetic, there are 
> several other minerals that may be attracted to a
> magnet(anistrophy of 
> magnetic susceptibility(AMS)). 
>
<http://www.galleries.com/minerals/property/magnetis.htm>
> 
> I am intrigued by the apparent attractiveness of the
> plant stems on your 
> magnet--any theories?
> 
> Elton
> 
> 
> 
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