Langres        47°51’38’’N, 5°18’49’’E

Champagne-Ardenne, France

Find: 2004

Classification: Ordinary chondrite (L4)

History: Mr. Jacques Bochaton discovered a broken rusty rock partially surrounded with a fusion crust among old rocks and pieces of stained-glass windows in a heap of rubbles that was found next to a low wall surrounding the field of an old chapel 10 m away, at "Sainte Anne farm," and situated about a kilometer from Langres. Years later, he decided to send pictures of various samples to MNHNP and sent a small broken samples to Jean-Claude Lorin de la Grandmaison, who cut it and sent additional pieces to Catherine Caillet Komorowski in order to make sections to be classified.

Physical characteristics: The whole rock initially measuring 79 × 72 × 40 mm is a fragment that weighed 340 g. Fusion crust is present on the sample that appears quite rusty. Millimeter-sized chondrules are visible on the surface.

Petrography: SEM investigations reveal a chondritic structure displaying a wide range of chondrule sizes. It shows numerous densely well-defined chondrules (the smallest is about 150 μm in diameter and the largest is 4.6 mm) juxtaposed in a sparse relatively coarse-grained microcrystalline matrix. Chondules have various textures and contain much more pyroxene than olivine crystals. Some tiny barred olivine chondrules coexist with large porphyritic chondrules with devitrified and partially recrystallized glass. Metal is very rare compared to sulfide. However, few μm-sized FeNi metal grains are present in olivine crystals or in silicate aggregates associated to the only one large metal-rich area found in the matrix. We found one 1600-μm black pyroxene fine-grained inclusion enclosing metal grains and distinct Ni-rich and Ni-poor sulfides. 300 μm-large chloroapatite associated with opaque mineral phases is also present interstitially in the matrix. Small merillite blebs are poikilitically enclosed within olivine. Large sulfide areas in the matrix exhibit triple-junction grains.

Geochemistry: Mineral compositions: EMPA of olivine and pyroxene crystals indicate small variations in chemical compositions of olivine Fa_24.4±0.9 (Fa_22.9-26.2, N=12) and low-Ca pyroxene crystals Fs_21.4±0.8 (Fs_20.3-22.7, N=9).

Classification: Ordinary chondrite (L4); Shock features are essentially ubiquitous irregular fractures in silicates whose visibility is enhanced by iron oxide creeping into the fractures. It is weakly shocked S2. Weathering is moderate W2-3.

Specimens: Mr Bochaton who collected the rock holds the main mass: 273.5 g. Two small samples (26.1 g + 10.5 g) totaling 36.6 g, one polished section, and one polished thin section are on deposit at MNHNP.