Flensburg        54°45.6873’ N, 9°22.7353’ E

Schleswig-Holstein, Germany

Confirmed fall: 2019 Sept 12

Classification: Carbonaceous chondrite (C1, ungrouped)

History: (D. Heinlein): The bolide was observed on September 12, 2019, at 12:49:48 (UT) by hundreds of eye-witnesses from the Netherlands, Germany, Belgium, Denmark, and the UK. The daylight fireball was registered by an all-sky meteor camera from Herford, Germany, and there are several casual videos recordings (dash and security cams) from the Netherlands and Germany. One day later, on the 13 September, a small meteorite fragment resulting from this event was found by accident by Mr. Erik Due-Hansen on the lawn of his front yard in Flensburg.

Physical characteristics: (D. Heinlein): A meteorite with a total mass of 24.5 g (roughly 3.7 × 3.5 cm in size) was recovered one day after the fireball event. The rock has a very fresh black fusion crust showing contraction cracks and a thin layer of brownish secondary fusion crust on several patches where the primary crust has been broken off. The meteorite has a bulk density of 1.984 g/cm3.

Petrography: (M. Patzek and A. Bischoff, IfP): Rounded to ellipsoidal relict chondrules (0.05 to ~1 mm in apparent diameter) and clusters of sulfide and magnetite grains are set in a dark, fine-grained matrix. The most abundant phases are different phyllosilicates and S-bearing phase(s) (probably tochinilite). The relict chondrules are free of any anhydrous silicates (such as olivine and pyroxene), contain abundant phyllosilicates and carbonates, and are often surrounded by sulfide laths. Troilite, pyrrhotite, and pentlandite were identified as sulfides. Carbonates occur as calcites, Mn-bearing dolomites, and a Na-rich phase. The mean apparent size of altered chondrules is ~150 µm.

Geochemistry: (M. Patzek and A. Bischoff, IfP): No olivine and pyroxene could be identified and analyzed. Defocused beam microprobe analyses (n = 135) revealed a bulk composition (in wt%) of: O: 32.0; Na: 0.29; Mg: 10.7; Al: 1.04; Si: 11.7; K: 0.04; P: 0.12; S: 2.04; Ca: 1.15; Fe: 16.0; Co: 0.03; Ti: 0.05; Cr: 0.25; Mn: 0.15; Ni: 0.85; Total: 76.3. O-isotopes (A. Pack; UGött): The oxygen isotope compositions of three analyzed fragments of Flensburg are: δ¹⁷O = 0.0806; -0.73023; -0.57844 ‰ and δ¹⁸O = 5.3032; 3.0272; 3.2993 ‰, Δ¹⁷O = -2.677; -2.304; -2.294 ‰ (relative to a reference line with a slope of 0.5305). The data are within the ¹⁶O-rich part of the field for CM chondrites.

Classification: Carbonaceous chondrite (C1-ung, W0). This meteorite is distinct from CM chondrites for the following reasons: chondrule apparent size (150 µm) is significantly different from that in CM chondrites (~270 µm), an heavily-altered CM would have a δ¹⁸O-rich composition compared to CM2 chondrites, Zn abundance (150 ppm) is too low for a CM (200 ppm without significant variations).

Specimens: Type specimen and PTS at IfP; the main mass is also at IfP.