Florida Clams Hold Glass Remnants from Ancient Meteor Strike

Some things are just worth the wait. His curiosity after 13 years finally paid off. 

Micheal Meyers, an assistant professor of Earth systems science at Harrisburg University of Science and Technology in Pennsylvania, discovered microtektites from ancient clams sample that they collected for a project as an undergraduate student. 

When the explosive impact of an extraterrestrial object is hurled into the atmosphere, particles called microtektites are formed. These particles then cool and crystallizes then fall back to the earth.

According to Meyers, in 2006, he and his fellow undergraduate students searched a Sarasota County quarry in the Pinecrest beds in Southern Florida for fist-sized time capsules of ancient environments. 

The students meticulously collected fossils from the walls of the quarry. Fossil clams were opened, and the sediments were strained through very fine sieves. The group is looking for benthic foraminifera, the single-celled organisms with shells taking a different shape depending on the environment it is from. 

Foraminifera provides a snapshot of their habitat 3 million years ago, the age where the beds were deposited. 

Aside from foraminifera, Meyers noticed the little glass spheres which were of the same size as the foraminifera. "They really stood out," Meyer revealed. Compared to lumpy, potato-shaped sand grains, the glass spheres were tiny, perfect spheres, he added. At that time, however, no one knew what it was. 

To satisfy his curiosity, Meyers collected 84 samples and processed them in the lab. He also emailed several experts to inquire about the spheres, but no one knew what they were, Meyers said. 

Two weeks after the discovery, the glass spheres were tested by X-ray spectroscopy. The finding, however, only indicated that it is "silica-rich."

Colleagues would regularly check on his spheres. He would also find his way through various laboratory equipment so he could get some free analyses done on the sphere. 

In 2018, he had a breakthrough: in his free time, he studied the elemental makeup and physical features of the spheres. This led him to infer that these are microtektites. He was also able to run the sample through a more sensitive X-ray spectroscopic analysis, which indicated that the mysterious spheres were microtektites. 

But, the mystery does not end there. 

The researchers intend to date the microtektites, but they guess that it is somewhere around 2 to 3 million years old. 

These particular microtektites have high sodium content, which is not the norm for microtektites. Microtektites are composed of silica, which generally does not contain sodium. When these microtektites were formed is still unknown. 

Salt is highly volatile and boils when but into the atmosphere at high speed. The sodium content in the indicates that the impact probably created a large reserve of rock salt or ocean, which points something close to Florida. The microtektites may be from meteor impacts near Florida Platform, Meyer said.

Unfortunately, the quarry where they collected the clams is now part of a real estate development; thus, there is no way to collect more samples.