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Sierra Gorda 012
Basic information Name: Sierra Gorda 012
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2018
Country: Chile
Mass:help 1100 g
Meteoritical Bulletin:  MB 108  (2020)  H4
Recommended:  H4    [explanation]

This is 1 of 6388 approved meteorites (plus 2 unapproved names) classified as H4.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 15 May 2019
Writeup from MB 108:

Sierra Gorda 012        22°30.198’S, 69°08.703’W

Antofagasta, Chile

Find: 2018 Apr 6

Classification: Ordinary chondrite (H4)

History: The meteorite was found on 6 April 2018 by Ilya Chaplygin during an expedition organized by Timur Kryachko.

Physical characteristics: The meteorite is covered by a thin film of weathered material. Fusion crust has been totally sand-blasted. The interior of the meteorite is gray to dark brown whereas the surface is dark brown.

Petrography: (Pavel Yu. Plechov, FMMR) Petrographic observation of a polished section shows chondrules with clear borders. Chondrules size up to 1200 µm. Porphyric olivine and olivine-pyroxene chondrules as well as nonporphyric pyroxene and barred olivine chondrules are present. POP chondrules consist of large homogeneous Ol crystals whereas Low-Ca Px occupies peripheral parts. Low-Ca Px often has clear zoning from very high-Mg relict parts (Fs1.8) to more ferrous rims (Fs14.8) in these chondrules. Matrix consists of tiny olivine and low-Ca pyroxene grains (near 1 µm) with Fe-Ni metal and troilite. Metal consists of kamacite and taenite (with 23-34 wt% Ni). Very rare Plagioclase grains (An1.9-3.5) are about 1 µm and only few are up to 3-5 µm. These features indicate a petrological type of 4 for the meteorite. Olivine shows no undulatory extinction. No shock veins or melt were found. Weathering products (goethite, "hydrogoethite") occur as veins and in situ alteration of FeNi metal.

Geochemistry: Mineral composition and Geochemistry: EDS-WDS analyses (Pavel Yu. Plechov, FMMR). Olivine Fa15.8±1.2 (N=48), orthopyroxene Fs11.2±3.1Wo0.8±0.6 (N=24), plagioclase Ab91.7An2.6Or5.1 (N=5), Cr-bearing clinopyroxene En49.9Fs15.4Wo34.2 (N=5), chromite Crt76.8Spl5.5 (N=6). Phosphates are both Cl-apatite and merrillite. Composition of kamacite (in wt%, N=5): Fe 92.4, Ni 7.1, Co 0.56 (measured by WDS). Taenite (N=3): 27.1 wt% Ni, 0.26 wt% Co. Troilite is close to ideal FeS.

Classification: Ordinary chondrite (H4).

Specimens: Ilya Chaplygin holds main mass. 61 g and thin section, FMMR.

Data from:
  Table 0
  Line 0:
Origin or pseudonym:plain
Date:2018 Apr 6
Mass (g):1100
Shock stage:S1
Weathering grade:W1
Fayalite (mol%):15.81±1.16 (N=48)
Ferrosilite (mol%):11.2±3.1 (N=24)
Wollastonite (mol%):0.83±0.55 (N=24)
Classifier:Pavel Yu. Plechov, FMMR
Type spec mass (g):61
Type spec location:FMMR
Main mass:Ilya Chaplygin
Finder:Ilya Chaplygin
Comments:Submitted by Pavel Yu. Plechov, pplechov@gmail.com
   and collections
FMMR: Fersman Mineralogical Museum, Leninskiy prospekt 18 korpus 2, Moscow, Russia, 119071, Russia; Website (institutional address; updated 24 Feb 2018)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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Public domain photographs:
Pavel Plechov   

     Recommended::   (22° 30' 12"S, 69° 8' 42"W)

     This is 1 of 2320 approved meteorites from Antofagasta, Chile (plus 9 unapproved names) (plus 1 impact crater)
     This is 1 of 2349 approved meteorites from Chile (plus 15 unapproved names) (plus 1 impact crater)
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