Life in the USA is not normal. It feels pointless and trivial to be talking about small looks at the fascinating natural world when the country is being dismantled. But these posts will continue, as a statement of resistance. I hope you continue to enjoy and learn from them. Stand Up For Science!
Tektite is from Greek τηκτός, tēktos, meaning ‘molten’; not to be confused with τέκτων, tektōn, for ‘carpenter, builder,’ the origin of the word tectonics. Tektites are impure glassy blobs of mostly silica, SiO2. They form as ejected drops of material that melted during an impact. They are similar to obsidian, natural volcanic glass, but tektites differ in having almost no water, which obsidian usually does, and they are usually fully glassy whereas obsidian often contains inclusions or segregations of crystalline material. They also typically show streamlined shapes and geometries indicating their flight through the air and landing on land or in water bodies.
There are four well-defined “strewn fields” where distinctive types of tektite are found, together with a few lesser occurrences. Three of the main strewn fields are confidently correlated with specific impacts: North American strewn field (Chesapeake Bay impact crater, 34 million years ago); Central European (Nördlinger Ries impact crater in Germany, 15 million years ago); and the Ivory Coast strewn field (Lake Bosumtwi impact crater in Ghana, 1 million years ago).
The other large strewn field is represented by tektite occurrences in Australia, Indochina, the Philippines, and much of the Indian Ocean, reaching 20% to 30% of the earth’s surface. They formed about 790,000 years ago, and the impact that created them had been unidentified, but recent work (Sieh and others, 2019, Australasian impact crater buried under the Bolaven volcanic field, Southern Laos: PNAS 117 (3), p. 1346) gives good support for the idea that the impact is buried beneath a young (mostly later than 700,000 years ago) volcanic field in Laos. Sieh and others used detailed geochemistry and stratigraphy, geophysics, and age dating to come to their conclusions. Wherever the impact was, it or the ensuing “rain” of tektites was likely noted by the Homo erectus population living in southern China at the time.
The two black tektites in my photo, each about 2.5 cm across, are from Thailand and are the Indochinite variety from the greater Australasian Strewn Field. They were given to me by Steve Koehler.
The tektites from Europe are called moldavites for their occurrence around the Moldau River in the Czech Republic. They are typically beautiful transparent glassy green; fake moldavites of green glass are abundant on the market and can sometimes be challenging to tell from real moldavites.
To be clear, these are not little meteorites; they are earthly material that was melted by the impact and ejected to solidify and fall back to earth, like the molten spatter from a volcano.
Cool Richard. I didn't know about the different, huge strewn fields. I'd guess there's a greater chance of finding a tektite than especially, an iron meteorite since there's more of them and they don't rust...
They are also found in California mohavie desert