[meteorite-list] Fwd: Rocks from Space Picture of the Day - January 26, 2009

From: Darryl Pitt <darryl_at_meteoritecentral.com>
Date: Mon, 26 Jan 2009 20:16:42 -0500
Message-ID: <712FD9B8-6222-4FC8-A27C-3220096DD135_at_dof3.com>

Thought it would be best to do a little checking:

WIKIPEDIA....

Almost all common metals, and many ceramics are polycrystalline. The
crystallites are often referred to as grains. Powder grains can
themselves be composed of smaller polycrystalline grains.

A crystallite is a domain of solid-state matter that has the same
structure as a single crystal. Metallurgists often refer to
crystallites as "grains".

Solid objects that are large enough to see and handle are rarely
composed of a single crystal, except for a few cases (gems, silicon
single crystals for the electronics industry, certain types of fiber,
and single crystals of a nickel-based superalloy for turbojet
engines). Most materials are polycrystalline; they are made of a large
number of single crystals ? crystallites ? held together by thin
layers of amorphous solid. The crystallite size can vary from a few
nanometers to several millimeters.




Begin forwarded message:

> From: Darryl Pitt <darryl at dof3.com>
> Date: January 26, 2009 8:00:04 PM EST
> To: Jerry Flaherty <grf2 at verizon.net>
> Cc: Meteorite List <meteorite-list at meteoritecentral.com>
> Subject: Re: [meteorite-list] Rocks from Space Picture of the Day -
> January 26, 2009
>
>
>
> Yes, quite right, the entire mass of many an iron meteorite is a
> portion of a broken or fragmented crystal.
>
> This is a (so cool) naturally faceted fragment that broke along
> crystalline planes.
>
> d,
>
>
>
>
> On Jan 26, 2009, at 6:07 PM, Jerry Flaherty wrote:
>
>> Why the word "crystal"?
>> ----- Original Message ----- From: "Michael Johnson" <michael at spacerocksinc.com
>> >
>> To: "Meteorite List" <meteorite-list at meteoritecentral.com>
>> Sent: Sunday, January 25, 2009 11:26 PM
>> Subject: [meteorite-list] Rocks from Space Picture of the Day -
>> January 26, 2009
>>
>>
>>> RSPOD:
>>> http://www.rocksfromspace.org/January_26_2009.html
>>>
>>> January 2009 Calendar:
>>> http://rocksfromspace.org/January_2009.html
>>>
>>>
>>> ______________________________________________
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Received on Mon 26 Jan 2009 08:16:42 PM PST