[meteorite-list] 'Mars' meteorite

[Gary K. Foote]

VERY very faint grey streaks.  VERY faint.

ary

On 9 May 2006 at 19:14, Bill Southern wrote:


> 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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> 

> 

> 

> southerndesert at yahoo.com

> http://www.NuggetShooter.com

> 

> 

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