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MINERAL OF THE MONTH

January 2012 - Mary Ellen Jasper

Mary Ellen Jasper

The mineral of the month for this update is Mary Ellen Jasper. Unless you live in Minnesota, you may not be familiar with this interesting form of microcrystalline quartz. This rock formed more than two billion years ago in the area that is now the Mesabi Iron Range in Northern, Minnesota. At that time one of the early life forms evolved in the ancient seas. These blue-green single-celled cyanobacteria contained chlorophyll and were able to harvest the energy of the sun to photosynthesize and produce their own food. Energy from sunlight was used to split carbon dioxide into carbon and oxygen. The carbon was absorbed, becoming part of the growing organism, and the oxygen was released into the atmosphere. Prior to the evolution of cyanobacteria, there was almost no oxygen in the atmosphere. Once these organisms developed, they proliferated and helped to trigger drastic changes in the earth's atmosphere, climate, and environment.

Some of the cyanobacteria lived in colonies that produced macro-scale structures called stromatolites. A drawing depicting what a stromatolite shoreline may have looked like during the latter part of the Archean period is shown below. Evidence of fossil stromatolite formations have been found throughout the world so these mushroom-shaped mounds dominated the shores of all the newly developing landmasses, including the area where the Mary Ellen Jasper developed.

Archean Eon Shoreline

The earliest stromatolite of confirmed origin dates to 2,724 million years ago. A recent discovery, however, provides strong evidence that microbial stromatolites extending as far back as 3,450 million years ago. These organisms were extremely resilient and adaptable, allowing them to be a major constituent of the fossil record for the first 3,500 million years of life on earth, with their abundance peaking about 1,250 million years ago.

Until the mid-1950s, scientists thought that stromatolites were long since extinct. That all changed in 1956 when living stromatolites were found in the Hamlin Pool located on the south end of Sharks Bay in Western Australia. Since then, live stromatolites have also been found in several sites in the Bahamas. Pictures of both are included below.

Stromatolites Sharks Bay
Stramatolites Bahamas

Stromatolites are stony structures built up by algae and cyanobacteria. The microbes live in gooey mats on the top surface of the structures. These mats trap fine sediments carried across them by tidal currents. As the mats fill in with sediments and become opaque, the microbes move upwards seeking sunlight. Stromatolites differ from normal fossils because they are formed by the activities of micro-organisms. They result from a combination of trapping, binding and precipitation of sediment.

One of the biggest impacts that stromatolites had on the earth was the release of free oxygen, which was a byproduct of their photosynthesis. When stromatolites first evolved, the earth's atmosphere had less than one percent oxygen. After the stromatolites evolved, significant amounts of oxygen did not accumulate in the atmosphere right away because of the vast quantities of oxidizable materials in the earth's crust as well as the dissolved eager-to-combine iron in the oceans. For more than a hundred million years, these materials absorbed any free oxygen that was produced. Mary Ellen Jasper developed not only from the remains of the stromatolites, but also from the oxidization of iron that was present in the area that is now northern Minnesota.

A few more pictures of Mary Ellen Jasper are included below. The first two pictures are of a thin polished slab. The first is displayed with front lighting and the second with back lighting.

Mary Ellen Jasper
Mary Ellen Jasper

Coincidently, I just polished a piece of Mary Ellen Jasper for a customer a couple of days ago. Here is a picture of that specimen.

Polished Mary Ellen Jasper

 

 


Mineral of the Month Archives

May 2007: Rainbow Fluorite

June 2007: Lake Superior Michipicoten Agate

July 2007: Labadorite

August 2007: Rain Flower Agate

Fall 2007: Malachite

December 2007: Nepheline Syenite

January 2008: Native Copper

February 2008: Amazonite

June 2012: Moqui Marbles

March 2008: Lake Superior Agate

April 2008: Shadow Agate

May 2008: Apohpylite

June 2008: Ocean Jasper

Summer 2008: Marra Mamba Tiger's Eye

September 2008: Mohawkite

October 2008: Mexican opal

November 2008: Prehnite

December 2008: Picture Jasper

January 2009: Sea Shell Jasper

February 2009: Polychrome Jasper

March 2009: Selenite Desert Rose

Spring 2009: Coyamito Agate

July 2009: Obsidian Needles

August 2009: Goethite

September 2009: Banded Iron Formation

Fall 2009: Fairburn Agate

March 2010: Fossilized Dinosaur Bone

April/May: 2010 Kentucky Agate

June 2010: Nantan Meteorite

July 2010: Mookaite Jasper

Aug/Sept 2010: Polyhedroid Agate

Fall 2010: Ammonite Fossil

Winter 2011: Argentina Condor Agate

Spring 2011: Petrfied Wood

September 2011: Petoskey Stones

January 2012: Mary Ellen Jasper

March 2012: Mexican Crazy Lace Agate

September 2012: Chlorastrolite Greenstone

March 2013: Jacobsville Sandstone

August 2013: Unakite

November 2013: Skip-an-Atom Agate

April 2014: Tiger's Eye

September 2014: Black Corundum

February 2015: Condor Agate

June 2015: Petoskey Stone

November 2015: Slag

June 2016: Lake Superior Copper Replacement Agates

August 2016: Puddingstone


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