[Rockhounds] Pics for id

[Jim Murowchick]

Aaron--
#1 is jasper--fine-grained quartz with hematite (iron oxide) and iron
oxyhydroxides as red and orange pigments.
#2 & 3 do look like petrified wood--can you see any cellular structure or
growth rings on the end with a magnifying glass?
#4 is a limonite concretion.  These sometimes form when a sulfide mineral
like pyrite gets oxidized.  It is mostly iron oxyhydroxides like goethite
(FeOOH), but might also contain (someone correct me if I'm wrong here)
lepidocrocite (also FeOOH) and possibly some clays mixed in.  Sometimes the
hard outermost layer is hardened with silica (quartz) or siderite (iron
carbonate) due to reactions with the surrounding materials when the
oxidation takes place.  Silica can form if the pH drops (becomes more
acidic), and pyrite oxidation produces sulfuric acid.
#5  Thought I might know what it was, but after looking at it again, I threw
that idea out.  I see the grooves and scratches that indicate how soft it
is.  It might be a piece of lead, though it looks very dark in the photo.

Jim
Dr. James B. Murowchick
Associate Professor, Geochemistry and Mineralogy
Department of Geosciences
University of Missouri-Kansas City
5110 Rockhill Road  /  420 Flarsheim Hall
Kansas City, MO  64110
816 235-2979   murowchickj at umkc.edu




On 7/27/09 5:21 PM, "Dennis Buffenmyer" <buff1 at ptd.net> wrote:

> leinani35 at yahoo.com wrote:
>> Ok, I was finally able to join the rockhounds.ning.com and post my pictures
>> that we need help with the id's. As far as copying the links to the pics,
>> beats me! Not sure how to do that. I know I created an album called Rock ID
>> and uploaded 5 pics to it named: Rock ID 001 - Rock ID 005. My name is Shawn
>> Hendricks and the info on the pics is copied again below. If anyone is able
>> to help, I sure appreciate it.
>>  
>> Hello Everyone,
>> Could you please help us with what these are?
>> 
>> pic 001 we are not sure
>> 
>> pic 002 we think is petrified wood, we found at the bottom of Overholser
>> Dam in OK
>> 
>> pic 003 another pic of 002
>> 
>> pic 004 Aaron wants to know what this is or what this would have been
>> maybe if he did not crack it open. The center is red and chalky but seems to
>> get harder as we scrape it but I told him to stop.
>> 
>> pic 005 This is dense, and it writes, Aaron thinks lead?
>>  
>> Thank you all,
>> Shawn
>> 
>> 
>> 
>>  
>> 
>> 
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> ok here's my guess...
> #1 agate or agatized something.. perhaps wood??
> #2&3 yep petrified wood...
> #4 most assuredly a goethite geode or bomb... more common in Pa..
> #5 going to go WAY out on a limb here and suspect something very fibrous
> such as a riebeckite or crocidolite, but that would only be a guess, if
> it is even a natural mineral and not something man made.
> REMEMBER!!! guesses only....