|Basic information||Name: Novato|
This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes
Year fell: 2012
Country: United States
Mass: 314 g
This is 1 of 9968 approved meteorites (plus 3 unapproved names) classified as L6. [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
|Comments:||Approved 24 Jan 2014|
Writeup from MB 103:
Novato 38.10900°N, 122.61053°W
Marin County, California, United States
Fell: 17 Oct 2012, 19:44 PDT (UT-7)
Classification: Ordinary chondrite (L6)
History: (P. Jenniskens, SETI): A bright fireball was widely observed and photographed from locations in and around the San Francisco Bay Area. The fireball passed the video camera fields of the NASA Cameras for Allsky Meteor Surveillance (CAMS) project. The calculated trajectory had an apparent entry speed at 89 km of 14 km/s. The downward projected path calculated by J. Albers predicted 1 g fragments fell near Bodega, 100 g fragments near Novato and 1 kg fragments near Sonoma. The trajectory was published in the San Francisco Chronicle, which led reader L. Webber of Novato to search her yard on Oct. 20. She remembered hearing the sound of an object hitting the roof of her garage that Wednesday night. At the side of the garage, she found a dense 61.9 g stone (numbered as stone N01), which was strongly attracted to a magnet. During investigation of this potential find, neighbor L. Rivera identified an impact divot on the roof of the Webber residence, shaped and positioned consistent with a meteorite from this fall hitting the roof and landing at the recovery site. A second 65.8 g stone was found in Novato (N02) by Brien Cook on Oct. 22, initially thrown out, but based on the Webber find, retrieved, cut, and recognized as a meteorite on Oct. 24. As of Oct. 30, 2012, four confirmed meteorites had been recovered with a total mass of 314 g. A tally is maintained at the Novato Meteorite Consortium website.
Physical characteristics: The stones are difficult to differentiate from terrestrial rocks. Even the freshly fallen meteorites have a thin brownish and irregular layered fusion crust and irregular dark and light interior. The recovered stones have a rounded shape. They are dense and respond to magnets.
Petrography: (A. Rubin, UCLA): A slice of stone N02 contains ~55 vol.% chondritic clasts and ~45 vol.% shock-darkened material. The fragment examined for petrography was from stone N01. Silicates have weak mosaic extinction. Plagioclase grains range from 50-200 μm. There are numerous troilite veins traversing large portions of the rock (silicate darkening). Chromite grains are fractured; many have troilite veins transecting them. There are a few chromite-plagioclase assemblages. One 12 × 20 μm grain of metallic Cu was found. Some of the troilite grains are polycrystalline. There are some patches where plagioclase has been melted and mobilized. There is localized melting around some of the metal and sulfide grains. There are a few silicate shock melt veins replete with small metal and sulfide blebs. The chondritic clasts have far fewer veins and contain moderately large, highly recrystallized barred olivine and porphyritic olivine-pyroxene chondrules that are well integrated into the matrix. These chondritic clasts are much lighter-colored in transmitted light than the matrix of the rock.
Geochemistry: Olivine Fa24.1±0.4 (n=21); low-Ca pyx Fs20.7±0.5 Wo1.5±0.2 (n=22); Ca-pyx Fs8.0±0.7Wo44.7±0.8 (n=5). The chromite grains (n=11) are somewhat richer in Al2O3 (6.4 wt.%) and MgO (3.4 wt.%) than unshocked ordinary-chondrite chromite, but are more characteristic of shocked and shock-melted chromite grains. Most of the metallic Fe-Ni is taenite with 77.7±5.0 wt.% Fe, 21.4±5.4 wt.% Ni and 0.51±0.18 wt.% Co (n=18). Only one kamacite grain was identified (7.2 wt.% Ni and 1.1 wt.% Co). The Co content of this single grain is intermediate between the ranges for L (0.70-0.95 wt.% Co) and LL (1.42-37.0 wt.% Co) chondrites, but is closer to L. Plagioclase: Ab86.0±0.6Or7.0±0.4 (n=14) is richer in alkalis than typical ordinary-chondrite plagioclase, and probably reflects shock melting. Troilite (n=10) is essentially pure FeS; it contains no detectable Cr, Co or Ni.
Classification: L6 breccia, unweathered W0, and moderately shocked S4.
Specimens: The Webber and Rivera families made 56 g of stone N01 available for study in the Novato meteorite consortium. 20 g of stone N01 is currently preserved at UCLA, unless material from other stones eventually replaces this material as part of the type specimen.
UCLA: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (institutional address; updated 17 Oct 2011)
SETI: SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, California 94043, United States (institutional address; updated 22 May 2012)
|References:||Published in Meteoritical Bulletin, no. 103, in preparation (2014)|
This is 1 of 253 approved meteorites from California, United States (plus 24 unapproved names)
This is 1 of 1787 approved meteorites from United States (plus 352 unapproved names) (plus 28 impact craters)
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