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Meteorite or Meteorwrong

Iron-Oxide Concretions and Nodules

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Vermont


Wisconsin


Left: Wyoming; Right: Texas


Ohio


Technically, this one is probably not a "concretion," but it's rich in hematite.


Texas


Two views of one from Pennsylvania


Maryland


Nevada, two views This grape-cluster texture is known as “botryoidal.”


Madagascar, two views


A beautiful specimen from somewhere in the U.S.

Utah

Top and side of one from Connecticut


Ontario


Utah


Texas


somewhere in Canada


Colorado


Oklahoma

South Dakota

Two views of a stone from South Carolina. This one and several others here were found by hunters.


Mexico


Illinois

Texas. This grape-cluster texture is known as “botryoidal.”


Somewhere, botryoidal


Lebanon

Texas. This concretion appears to have started as a mass of pyrite crystals (iron sulfide, cubic) and is in the process of oxidizing to iron oxide.

This is a cluster of pyrite crystals beginning to oxidize to hematite.

This thing started out as a several pyrite crystals but is now largely oxidized to hematite.


Pennsylvania


This one is fascinating in that one side (top) has a texture like some other concretions shown here but the other side (bottom) has features that resemble meteorite regmaglypts.

West Virginia. This grape-cluster texture is known as “botryoidal.”

This photo was sent to me by a fellow who found it while gardening in his yard in Kauai, Hawaii. I asked a colleague who lives in Kauai whether or not hematite concretions were found there. He said that limonite concretions did occur. Limonite is a mixed iron oxide-hydroxide. It's possible that some of the other concretions depicted here contain limonite.

 

This one was sent to me from Iowa. It makes a red streak and does not attract a magnet, but the specific gravity is only 4.1. Pure hematite has a specific gravity of 5.3, so this rock must contain some low-density mineral like quartz or a carbonate in addition to hematite.

I suspect that this one, from Delaware, also contains mineral phases other than hematite.

This one also looks like hematite cement holding sand grains together.

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Prepared by: Randy L. Korotev

Department of Earth and Planetary Sciences
Washington University in St. Louis

Please don’t contact me about the meteorite you think that
you’ve found until you read this and this.

 

e-mailkorotev@wustl.edu

Last revised: 8 October 2018