Diepenveen (CM2-an) is officially registered in the Meteoritical Bulletin

01/01/2016 10:02 · by karmaka · in carbonaceous chondrite, CM, Diepenveen, meteorite, witnessed fall

“Diepenveen 52° 17′ 35″N, 6° 7′ 30″E

Overijssel, Netherlands

Probable fall: 1873

Classification: Carbonaceous chondrite (CM2, anomalous)

History: (M. Langbroek, Naturalis and DMS, N. de Kort, KNVWS): A single 68-g stone in private ownership of Mrs. Leida Kiers was recognized as a meteorite by retired Royal Eise Eisinga director Henk Nieuwenhuis in 2012. A late 19th century handwritten card signed by D. H. Te Wechel, son of the 1873 Diepenveen village teacher, is preserved with the meteorite. It describes how the meteorite fell on 27 October 1873, near 3 pm local time, in an agricultural field near Diepenveen village. It fell near farmhand A. Bos and his wife, who reportedly recovered it within ‘ of the fall. The owner of the land is mentioned as J. W. Ilsinck, allowing to trace the fall location to within a few hundred meters through historic archives. The meteorite entered the curiosity collection of the Rijks HBS (Higher Civilian State School) of Deventer shortly after the fall and resided there for over a century. When the school permanently closed down in the 1970s, the meteorite and accompanying documentation were rescued from destruction by a teacher, Mr. Jager. After his death, it entered the private rock collection of Mrs. Kiers, who donated the meteorite to NBC in October 2013. All persons and places mentioned have been traced in historical archives.

Physical characteristics: (M. Langbroek, NBC): Upon rediscovery in 2012, the single preserved stone consisted of a fresh-looking 68.4 g half individual with a break surface and approximately 50% mostly shiny black fusion crust. The interior is dark grey-black with light spots. It is very crumbly. A small several grams detached fragment of the individual stone was glued back to it at an unknown date (perhaps shortly after the fall).

Petrography (L.M. Kriegsman, Naturalis): The meteorite is a breccia with angular clasts of different lithologies measuring up to 1 mm. The different lithologies vary with regards to chondrule rim thickness, and hydration level of matrix. Chondrules make up 15–20 vol% of the mass. Chondrule size is mostly between 0.05 and 0.7 mm with a mean of 0.35 mm, one measured as large as 1.8 mm. Most chondrules are porphyritic, only very few barred chondrules are present. They have fine grained dust mantles, locally showing alteration to tochilinite. The matrix contains Fo grains up to 0.4 mm, as well as amoeboid olivine aggregates and CAIs dominated by fassaite with perovskite in the core. Pyroxenes show two types: low-Ca pyroxene (monoclinic state confirmed by Raman) and fassaite. Matrix metals: 2-6 vol% of the matrix is metal and sulfides. FeNi grains occasionally measure up to 0.5 mm. All FeNi metal is kamacite with up to 2 wt% Cr and 1 wt% P. Magnetite is absent. Rare, tiny carbonate grains are present.

Geochemistry: Mineral compositions (EPMA and SEM-EDS) and geochemistry (L.M. Kriegsman, NBC; K. Ziegler, UNM; M. Zolensky, JSC; W. van Westrenen, VU Amsterdam;): Fa9±13 (chondrules, N=23), Fa35±10 (matrix, N=5), 70 (barred, rare, N=1); Fs2±1Wo2±2 (low-Ca pyroxene, N=8), Fs1.8±0.2Wo44±4 (fassaite, N=5). Oxygen isotopes (17 measurements): δ17O = -12.42, -12.75, -12.25, -11.88, -11.90, -11.19, -11.03, -9.55, -8.41, -7.36, -5.98, -4.31, -1.93, 0.30, -1.17, -0.24, -0.04 (range -12.748 to +0.301), δ18O = -10.33, -10.14, -9.59, -9.58,-9.22,-8.27,-8.15,-6.80,-5.24,-4.34,-2.11, 2.50, 5.55, 5.77, 5.93, 6.95, 7.69 (range -10.328 to +7.698), Δ17O = -6.96, -7.40, -7.19, -6.83, -7.03, -6.82, -6.73, -5.96, -5.64, -5.07, -4.86, -5.63, -4.86, -2.75, -4.30, -3.91,-4.10 (range -7.396 to -2.746). Some lithologies have more Fe-rich olivine: Fa38-64 (average Fa53, N=9), and their matrices contain significantly less phyllosilicates that the remainder of the meteorite.

Classification: CM2-anomalous. The classification as anomalous is based on the oxygen isotopic data, which are outside the range of CM bulk samples. This meteorite also hosts metal in the matrix, rarely observed in normal CM2 chondrites, suggesting a more reduced character for this meteorite.

Specimens: Main mass (66.6 g) at NBC. Thin section at JSC.”