Kendleton
Stone. An L4 Olivine-hypersthene chondrite,
a fragmental regolith breccia with a Shock Rating of S3
Fell May 2,1939,
Fort Bend County, TX.
 The "La Tribuna Illustrata" cover from May 21st 1939. The watercolored drawing by artist Vittorio Pisani shows a Houston street scene with a crowd terrified by the spectacular Kendleton fireball crossing the sky, 44 miles W. by S. of Houston, witnessed by hundreds on May 2, 1939.
Our friend Russ once said “Kendleton is a breccia with a huge mixing of other material. It's akin to
a cosmic bus that seemed to stop along its journey picking up homeless, indigent little relics of past collisions looking for a ride to the, then unformed, Earth!”
The recovery of specimens from the Kendleton fall was one of calculated science: Observations of the fireball and photographs of the resulting trail were used to trace the path the meteorite took to earth.
A total of 6937g were recovered from its strewn field in the form of 13 complete stones and 15 fragments. The largest specimen weighed 1.6 kg and went into the O.E. Monnig Collection (1939).
Here's a picture of a beautiful 25.4 g slice:
From New England Meteoritical Services
As you can see Kendleton is chondrule-rich, and contains visible L3, L5, L6 and trace carbonaceous clasts in its groundmass.
Analysis
What the cosmic bus picked up is really amazing.
Regolith breccias are fragmental rocks that contain implanted solar-wind gases. Regolith breccias are also widely believed to have formed by lithification (the process by which unconsolidated materials are converted into coherent solid rock, as by compaction). The regolith material once resided at the surface of a asteroid type body.
About 80% of the Kendleton meteorite consists of a dark chondritic type-4 matrix with at least four other types of light & dark colored clasts:
- Light-colored type-5 clasts with less-defined chondrules than the type-4 host matrix,
- Light-colored primitive type-3 clasts which are likely L3.5.
- Shock-blackened clasts and
- Melt-rock clasts.
The shock-blackened clasts were produced in post-metamorphic impacts, while the melt-rock clasts were formed before the end of the metamorphism.
The shock-blackened clasts are angular to irregularly shaped with sharp to diffuse boundaries. They consist of faint, isolated to grouped chondrules; shock-melted Iron/Nickel (Fe/Ni) & Troilite (FeS); glassy material and olivines & pyroxenes.
- A unique tridymite-rich inclusion was also found during studies which is believed to originate from the H-Chondrite parent-body, due its matching oxygen isotope.
It was described as an inclusion and not a clast because there was no textural evidence that it was broken from a pre-existing rock -- although given its relatively large size, this is likely.
Here's another picture which shows some of the clasts:
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From www.meteorite.com
Terms
As we have seen with other meteorites, Kendleton is a wonderful teaching example. Here's some of the terms used to describe the meteorite.
Definition of Breccia
- n. A course-grained rock, composed of angular, broken rock fragments held together by a mineral cement or a fine-grained matrix.
Here's an example:
Definition of Clast ( -s)
- n. A fragment of rock.
Here's a picture of a clast:
Photo from http://www.lexic.us
Definition of Troilite
- n. Native iron protosulphide, FeS. It is known only in meteorites, and is usually in imbedded nodular masses of a bronze color.
Here's a picture of a troilite inclusion:
Photo from http://www.lexic.us
Definition of Inclusion
- n. Any small fragment of something found within another body.
Here's a picture of an inclusion:
Photo from New England Meteoritical Services
Definition of “melt”
- n. The substance formed when extreme heat is generated as the result of the impact shock of a large meteorite.
What's difficult about showing this definition is that it is something that you learn by seeing lots of examples. Here's two:
Photo from http://www.lexic.us
Here's another:
Basically, when the pressure of an impact is great, the fragmented rocks melt in the extreme heat that is produced – and all of this comes about in seconds.... Also, impact melts are composed predominantly of the target rocks, but can contain a small but measurable amount of the impactor.
In this process, you can find small particles dispersed in various impact deposits and ejecta, larger pools and sheets of melt that coalesce in low areas with the crater.
Definition of Regolith (s)
- n. A layer of loose rock.
Here's an example of lunar regolith:
Photo from http://www.lexic.us
Here's an earth-based example:
Photo from http://www.lexic.us
Definition of Tridymite
- n. Pure silica, like quartz, but crystallizing in hexagonal tables.
Here's a picture of white tridymite hexagonal crystals
From http://www.galleries.com/minerals/silicate/tridymit/tridymit.htm
Links
Here's a scientific report focused on the origins of Fragmental and Regolith Meteorite Breccias:
http://www.meteorites.com.au/features/Kendleton1.pdf
Here's another scientific report about the history of the surface of the Kendleton parent body:
http://www.meteorites.com.au/features/Kendleton2.pdf
Here's two dictionaries for reference:
http://www.science-dictionary.org/
Lexic also includes excellent pictures:
http://www.lexic.us/
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