Mercantour        44.145°N, 7.311°E

Provence-Alpes-Cote d’Azur, France

Find: 2014 Sept 25

Classification: Ordinary chondrite (L4-6)

History: A systematic search of moraines and rocky surfaces by Eric Paillery led to this single discovery in the Southern Alps granitic massif, within Mercantour National Park, near 2900 m elevation.

Physical characteristics: A single angular fragment, covered ~30% by a relatively fresh fusion crust. Gray color with minor rust spots. Inner surface sometimes covered by a carbonate rind. Little patina visible. A few small rounded quartz grains inserted in cracks, with a light-orange soil matrix.

Petrography: Breccia with type 4 to 6 clasts (major class 4 to 5). Distinguishing type 4, 5 and 6 was done based on polished section observation of the morphology and overall texture of chondrules and metal grains. Mean chondrule diameter 707±39 μm. One fine-grained clast with low metal and troilite content was observed. Weathering at microscopic scale is hardly detectable but macroscopic rust spots indicate W1.

Geochemistry: Type 6 lithology: olivine Fa_27.7 (n=1), orthopyroxene Fs_21.2Wo_0.7 (n=1). Type 4 lithology: olivine Fa_24.7 (n=1), orthopyroxene Fs_20.2Wo_2.1 (n=1).

Classification: in the L group is based on magnetic susceptibility and chondrule size. Petrography (SEM and reflected optical microscopy) indicates a L4-6 breccia.

Specimens: 22.6 g at CEREGE.