[meteorite-list] Moqui Marbles
From: David Freeman <dfreeman_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:34 2004
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Dear Robert and List;
<br>How about a test for nickel or rare earth's content on the marbles.
Would not that help distinguish terresterial/non teresterial origin?
<br>Our iron concreations up here in Wyoming seem to humorously immitate
human body parts quite frequently. I have a thumb, foot, and an amazingly
accurate stone heart in my collection of sandstone oddities of nature.
<br>Entry level rock collectors treasure their finds and sometimes have
a hard time understanding that it isn't a dinosaur body part...or a paleo
indian body part.... This situation seems
to be just another cross to bear for the learned mineral and meteorite
<p>Robert Verish wrote:
<blockquote TYPE=CITE>REF: <a href="http://www.rocksnstuff.com/specimens/moqui.htm">http://www.rocksnstuff.com/specimens/moqui.htm</a>
<p>Last weekend I had a display case at the San Fernando
<br>Gem Fair in which I would show a meteorite, and then
<br>right beside it, a look-a-like meteor-wrong. One of
<br>these meteor-wrongs that I had displayed was a "Moqui
<br>Marble", which I had labeled as a "limonite/hematite
<br>concretion in sandstone". My explanation for how
<br>these stones were formed started a lively debate among
<br>the rockhounds in attendance at the show.
<p>What I would like to ask you is what do you know about
<br>the origins of these remarkably similar-shaped stones?
<br> I know Dave Freeman has a comment or two that he
<br>could make about these stones, but since you have been
<br>doing impact-related field work close to this area, I
<br>thought I would give you first crack at this topic.
<p>It just so happens that one of our own brethren
<br>[geologist] has muddied the waters, regarding the
<br>origins of these stones. ("My sediments exactly."
<br>said another geologist friend of mine.;-)
<p>Here is what he had to say regarding these stones, at
<p>"This material was formed in an impact site 12 miles
<br>east of Escalante UT in an area known as 'Big Spencer
<br>Flat'. The 'marbles' are composed of millions of
<br>molten spheres condensing on sand grains that bumped
<br>into and joined with other grains to form small
<br>spheres that joined with others to become even larger,
<br>with the hematite/silica coating always moving to the
<br>outside, but leaving a thin coat on most sand grains
<p>"Some larger spheres cooled below the melting point
<br>during this process, so all steps of it can be seen.
<br>Some 'marbles' landed in sand, others in limestone,
<br>some have joined in almost every way imaginable. Most
<br>of the crater has eroded away, but the remnants of
<br>dikes created in the impact are still visible.
<p>"The principle collecting area is in the new Escalante
<br>Monument, but material was deposited on top of eroded
<br>Navajo Sandstone as far as Lake Powell. I have yet to
<br>determine if reports from Scofield Reservoir could be
<br>the same formation, or a different impact. I am sure
<br>the same process has produced 'Indian Paint Pots' in
<br>sandstones from many time frames all around the world,
<br>and are much like 'tektites.'"
<p>The above quote is from Dave Cosby, a geologist who
<br>has been doing some research on the Utah area where
<br>Moqui Marbles are found. Dave believes that the
<br>uniformly shaped stones were the result of a meteorite
<br>impact in that area.
<p>While we're on this subject, here is a "heads-up" for
<br>the members of our eBay "Wrong Squad" - at these URLs:
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Received on Thu 01 Mar 2001 10:52:00 AM PST