Rocks

SCOLECITE, STILBITE-Ca, and CALCITE and VANADINITE specimens

These are pictures of a few selections in our collection.  The Scolecite, Stilbite-Ca and Calcite (about 12 inches long) was from Sami Makki, whose grandfather started the rudiments of Matrix India in the 50’s.  Sami’s father Muhammad and he now run the operation that began exporting minerals in the 70’s.  Sami personally collects much of the material and he personally collected this and other specimens we have. The specimen comes from the basalt plains in Maharashtra, India. 

Sami was called by a construction crew about a potential pocket of minerals found during the digging of a well.  (Sami and his team have networked with construction companies all over India and often get calls in addition to the mines they operate.)  The well wall started gushing water and they quit for the day.  Next day they realized they hit a pocket of water and called Matrix India to check it out before continuing to the actual water table.  Sami said these Scolecite formations take millions of years of still water to form in.  They then bring their own team in to remove the specimen material and reimburse the construction company.

I recently saw an article about research being done on these kinds of trapped water for bacteria that have been isolated for millions of years! The Vandinite is almost always found in oxidation zones around lead deposits (per Mindat.org).  These come from Morocco and exhibit brown and reddish-brown, two of the many colors this mineral can have.

Scolecite, Stilbite-Ca and Calcite
Photos by and from the collection of Steve Dumortier
Vanadinite specimen
Photo by and in the collection of Steve Dumortier
Vanadinite specimen
Photo by and in the collection of Steve Dumortier

PEANUT WOOD

Peanut Wood from Western Australia. It is petrified wood. It was driftwood that sank to the floor of a shallow sea. Then it was set upon by a bivalve called, Teredo or shipworm. It was covered with mud and the borings were filled with sediment which are the white areas. Formed during the Cretaceous Period, 120,000 million years ago.

Peanut Wood from Western Australia
Peanut wood from Western Australia

Photos by Dan Snow

Chemistry Rocks Webinar

chemistryrocksacs

The American Chemical Society is hosting a live webinar called “Chemistry Rocks! – Exploring the Chemistry of Rocks and Minerals” on Tue, Oct 24, 2017 from 6:00 PM – 7:00 PM CDT. We are surrounded by rocks and minerals everywhere…in the ground we walk on, the places we work and live, and even in the food we eat. How are chemists experimenting with these fundamental materials to help the world and make our lives better? Ask questions live to the experts regarding the amazing work that is being done in rock and mineral science.

To see the webinar, sign up at GoToWebinar and fill out the form. They will send you an email to confirm. Then, on Tuesday at 6PM Central Time, follow the link in the email, make sure you have your computer’s sound turned on, and enjoy!

Chemistry in Mining

During Earth Science WeekTM, we went to a lecture by Dr. Innocent Pumure from UCM called “Sonochemical Extraction of Arsenic and Selenium from Pulverized Rocks Associated with Mountaintop Removal Valley Fill (MTR/VF) Method of Coal Mining”.

You may be wondering, what is Mountaintop Removal Valley Fill Mining? First, the excavation company blows up (or strips) the top part of the mountain to remove vegetation and expose the coal seams. The coal seams are then mined through the open cast/strip method, and the extra rock and soil is dumped in nearby valleys called valley fills. It is cheaper and easier to do than regular mining, where they dig a vertical shaft down and do everything through the tunnel, but it blasts the mountain apart and looks ugly. Since 30% of electricity in the USA comes from coal, valley fill mining is still pretty popular.

In 2002, the EPA found too much selenium downstream of a certain mine in West Virginia (we’re not going to say which one). It was over 5 ng/mL, which was the limit back then.[*] 7 years later, there was still an active mine there and the water still had too much selenium. Even worse, the surrounding sediment had 10.7 mg/kg selenium. This could cause problems for the environment later. Due to bioaccumulation, you could say once it’s in there, it’s really in there.

So now we get to the topic of Dr. Pumure’s talk, in which he and his colleagues discovered a way to quickly find out how much selenium and arsenic were in the ground around this mine in West Virginia. When you do a chemical analysis, you usually have to break down the samples in order to measure what is in them. One method to do this would be to take some core samples and do an acid extraction, but that takes a long time and uses a lot of reagents. Sonochemical extraction uses ultrasound energy to accelerate the leaching process that would naturally happen as rocks become weathered. Since it is ultrasound, it does not directly touch the sample, is minimally invasive, and does not need any reagents except water.

Next, he explained the methodology, which means a description of exactly how they did it in the lab: the size of the extraction cells, how much water and power were used (200W/cm3), how long the samples were sonicated, and all the other pertinent information for chemists. Pumure actually spent quite a lot of time finding out the optimal sonicating time to get the best extraction. It turned out the best times for his sample sizes were 20 minutes for Se and 25 minutes for As. That’s really fast![**] Then, he did a comparison to a chemical sequential extraction to make sure that the sonochemical extraction method was getting everything. To summarize, yes it was. Finally, he did a principal component analysis of core samples from different places all over the mountain using this same technique. They found some really interesting trends and correlations, for example, it appears that there is more arsenic in illite clay than other types of clay.

This research has many useful applications. If you were running a mine, you could take samples more frequently to see if your mine is polluting the surrounding environment, and then you could do something about it before the EPA finds out. The method could probably be used for other analytes, too. For other research needs, you could now quickly analyze large batches of mineral samples to get lots of data that would otherwise be too expensive or time consuming to obtain.

[*]The EPA has since lowered the limit and now it is 3.1 ng/mL.
[**]For comparison, some of my colleagues do chemical extractions that take 2 days.

Mini Field Trip July 2017

After our meeting on July 15, 2017 we decided to go on another mini field trip and look for fossils. There were crinoid stems, composita, and other fossils, as well as lots of blue shale. There was also something red and nobody knew what it was. I don’t have many pictures because it was very hot outside and my phone said something about battery temperature too high.

Composita fossils found in Kansas City. lots of crinoid stems and little fossils of many shapes

Composita found in Kansas City. Photo by Stephanie Reed

blue shale rocks in a row from kansas city mo

Blue shale. Photo by Stephanie Reed

bird in a tree

David met a friendly bird. Photo by David Reed.

man bending over gathering rocks outdoors

This is a traditional pose for members of rock clubs. Someday we may make a calendar. Photo by Stephanie Reed