[meteorite-list] OT: For the Geologists and Math Wizards!

[MexicoDoug]

Jim,

In a practical sense, this is quite possible since there are more 
possibilities, where your question could be taken as too ambiguous.  
Specifics - what are you really after?  I'm thinking if this relates to 
meteorites you might have some concretions in mind as well, or perhaps 
melting and there are rarely "just" two minerals present in nature.  
When I mixed the concrete to fill the hole in the driveway, the 
hydration (a chemical modification) causes a structural change as well 
which contributes to a volume change, and it was certainly more slurry 
than the sum of the cement and sand, to adjust for the water.  Some 
hydrations are reversible and others aren't.  In nature for the 
organized mind, things usually go to hell in a handbasket since it is 
usually an open, complex system where everything and then some goes.

If you like math, some engineers probably are very concerned about 
shrinkage or expansion of concretions for the times we drive over 
bridges, etc:

maybe this gives further insight, I googled blindly:
http://www.byg.dtu.dk/upload/institutter/byg/nyheder/trb-06-1571-as%20submitted%20final.pdf

If two minerals are melted together, it is quite possible they will 
form a new crystal or amorphous structure, perhaps not even a clear 
chemical modification, but rather just reordering on a molecular scale 
that don't result in voids, but do result in a new density without 
adding gases, etc.  I guess it might be a new mineral, but I'm not sure 
I know the precise definition of a rock or mineral so I'd think of it 
this way.

Kindest wishes
Doug


-----Original Message-----
From: Chris Peterson <clp at alumni.caltech.edu>
To: meteorite-list <meteorite-list at meteoritecentral.com>
Sent: Sat, Apr 14, 2012 2:08 am
Subject: Re: [meteorite-list] OT: For the Geologists and Math Wizards!


If the two combine as some sort of conglomerate (like a breccia), and
the combination doesn't result in voids, then the bulk density can't be
lower than the density of the lowest density material. But if the two
combine chemically, resulting in an alloy or in the formation of
different minerals, certainly the bulk density could be lower than
either of the constituents (because you could have an increase in 
volume).

Chris

*******************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 4/13/2012 9:04 PM, Jim Wooddell wrote:
> Hi all!
>
> I have a question that relates to meteorites...sort of.
>
>
> If I have two minerals that are combined that have two different
> densities, could the bulk density ever be lower the density of the
> mineral with the lowest density?
>
> Examples (to make it easy) Mineral 1 = 3g/cc Mineral 2 = 15g/cc
>
> IOWs could I ever have a density lower than 3g/cc???
>
> If yes, can I please see the math?
>
> Thanks
>
> Jim

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