Famenin meteorite, Famenin County, Hamadan Province, Irani

Regional Level Types
Famenin meteorite	Meteorite Fall Location
Famenin County	County
Hamadan Province	Province
Iran	Country

Ordinary chondrite, unequilibrated (H/L3)
Fell, 27 June 2015; 630 g

During the early morning a loud sound on the roof led to the discovery of several small fragments of a small stone on the roof and yard. The meteorite is an unequilibrated chondrite with first indications of a composition on the borderline of the H and L ordinary chondrite chemical groups (high and low bulk iron, respectively). Small, but well-defined chondrules of different types (avg. diam. 615±380 µm) are found within a clastic matrix. Troilite rims are prominent on a number of chondrules and Fe-Ni metal is evident. Sulfides include pyrrhotite as well as the more common troilite.

Both olivine and orthopyroxene are unequilibrated making Famenin one of the small group of unequilibrated or type 3 ordinary chondrites which account for ~ 5% of all ordinary chondrites. Famenin is also one of only 4 observed meteorite falls that are currently classified as H/L chondrites at the Meteoritical Bulletin Database, three of them unequilibrated. The other H/L chondrites are the 1855 Bremervörde (H/L3.9) fall, the 1878 Tieschitz (H/L3.6)fall, and the recent 2007 Cali (H/L4)fall. Famenin is the only meteorite fall classified exactly as an 'H/L3' chondrite. Eight smaller finds in the 19 g to 375 g range are also listed [May 2016].

At the present time, a consensus does not appear to exist as to whether the H/L chondrites are actually derived from a separate original parent body (OPB), a mechanical mixture of H- and L-chondritic components, and/or whether they are an intermediate category reflecting the limitations of our classification system. For the record, Famenin has been deemed an H/L chondrite because: (1) Olivine composition is within the range of H chondrites; (2) Magnetic susceptibility is intermediate between H and L chondrites; (3) Bulk metal content determined by hysteresis measurements is in the L range. (4) Chondrule size is closer to the range for L chondrites than for H chondrites. Keep posted!

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References