Kirbyville meteorite, Jasper County, Texas, USAi

Regional Level Types
Kirbyville meteorite	Meteorite Fall Location
Jasper County	County
Texas	State
USA	Country

Eucrite, monomict
Fell 12 Nov 1906, 97.7 g


The Kirbyville eucrite is a small roughly pyramidal rock with a well-developed fusion crust of maximum dimensions of ~ 4cm. As with other eucrites pyroxene and plagioclase are its two primary constituents accounting for ~ 95wt% of the meteorite. The pyroxene (~58%) is mostly pigeonite, but a Ca-rich pyroxene phase is also present. Plagioclase (~37%) is anorthitic. Minor amounts of silica, ilmenite, and troilite with traces of chromite and Fe-Ni metal are also reported. Brecciation is ubiquitous, but small grains and clasts are a mixture of euhedral lathes and more angular fragments with occasional veins. A more or less expected U/He age of ~ 4.5 billion years is reported as well as 3.2 billion year K/Ar age. The latter age also attests to strong impact(s) somewhere between the asteroid Vesta — the putative home of most eucrites — and the small eucrite's eventual encounter with the earth.

Of the 34 recorded eucrite falls, Kirbyville is one of only 3 eucrites with less than a 100 g mass. Only the Medanitos (1953) and Nagaira (1875) falls had less mass. Finds are another matter. A total of 390 Eucrites are known with a mass of less than Kirbyville, mostly from Antarctica, including several with masses of less than a gram. Naturally enough Kirbyville and most of these very small stones have not been subject to intensive attention. Still, telescopic and spacecraft investigations of Vesta, spectroscopic and orbital studies of apparently Vesta-derived asteroids (Vestoids), and studies of large and small HED meteorites continue to strengthen the current belief that most - but not all - members of the HED clan (Howardites, Eucrites, and Diogenites) are fragments of Vesta. [A few look-a-likes such as the Ibitira 'Eucrite' can be excluded on the basis of their oxygen isotope ratios]. Kirbyville happens to be one of the smaller pieces of this panoply of conundrums.

Other Regions, Features and Areas containing this locality

References