Sinawan 005 Rumuruti Chondrite Main Mass, R5-6, 187.65g, Fusion Crusted

The main mass of Sinawan 005, a Rumuruti chondrite

This is the main mass of Sinawan 005, a Rumuruti chondrite classified as R5-6 and recovered near Ghadamis, Libya. The piece weighs 187.65 grams and is the largest surviving single piece of the stone, cut on one face to reveal the interior while retaining fusion crust across the exterior. The rest of the stone has been cut into slices, so this piece holds the greatest mass remaining from the recovered rock.

Rumuruti chondrites are one of the least common chondrite groups. The Meteoritical Bulletin lists Sinawan 005 as one of three approved meteorites classified as R5-6, so this main mass represents a scarce classification held in a single substantial piece.

Structure and features

The cut face shows a chondritic texture with chondrules and mineral clasts set in a fine matrix, the primitive texture that defines chondrites. The Meteoritical Bulletin describes two distinct lithologies in Sinawan 005. Lithology 1 is composed of well-defined chondrules up to 415 micrometers with chondrule fragments in a finely recrystallized matrix, and lithology 2 is composed of indistinct chondrules and mineral clasts in a fine, grayish matrix. Both are visible across the polished interior of this piece as tonal and textural domains.

The exterior carries fusion crust from atmospheric entry. The Meteoritical Bulletin records the stone as covered with 60 percent well-preserved fusion crust with cracks and 40 percent secondary fusion crust, desert varnished. The well-preserved primary crust appears as darker, glassier patches, with the secondary crust textured across the remaining surface. For more on how this surface forms, see what is fusion crust on a meteorite.

Discovery and provenance

Sinawan 005 was found in 2023 near Ghadamis, Libya, at 30 degrees 2 minutes north, 11 degrees 36 minutes east. It was recovered as a single rock of 507.2 grams and purchased in Morocco. The meteorite was classified by J. Garcia at ADARA and published in the Meteoritical Bulletin, MB 114. The type specimen of 20 grams is held at MUNA, with a 12.37 gram slice and a thin section at ADARA. The main mass is recorded in the Meteoritical Bulletin as held by Brian McDonald of Treasure Coast Meteorite Co., IMCA Member #3323, and this 187.65 gram piece is that main mass.

Scientific context

Rumuruti chondrites, abbreviated R chondrites, are a distinct group of chondrites named for the Rumuruti meteorite that fell in Kenya in 1934. They are highly oxidized, with almost all of their iron held in silicates and oxides rather than as free metal, which is why the Meteoritical Bulletin notes that no FeNi metal was observed in Sinawan 005 and the opaque minerals identified are pentlandite and magnetite. The petrologic designation R5-6 indicates a rock that experienced significant thermal metamorphism. Geochemistry for Sinawan 005 includes olivine at Fa41.4 and low-calcium pyroxene at Fs25.3, compositions consistent with the R chondrite group.

Frequently asked questions

What is a Rumuruti chondrite?
A Rumuruti chondrite, or R chondrite, is a rare group of stony meteorite that is highly oxidized and contains little to no free metal. The group is named after the Rumuruti meteorite that fell in Kenya in 1934. Sinawan 005 is classified as R5-6, indicating a metamorphosed member of the group.

What does the main mass of a meteorite mean?
The main mass is the largest single surviving piece of a recovered meteorite. For Sinawan 005 the recovered stone was 507.2 grams, and after the type specimen, an institutional slice, and additional slices were removed, this 187.65 gram piece is the largest piece that remains.

How is Sinawan 005 documented?
Sinawan 005 is an officially classified meteorite published in the Meteoritical Bulletin, MB 114, classified by J. Garcia at ADARA. The main mass is recorded in the Bulletin as held by Brian McDonald, who submitted the stone.

How should the specimen be stored and handled?
Handle with clean gloves and keep it in a dry environment. As a desert find it is best kept away from humidity to preserve the fusion crust and cut surface over the long term.

How do I verify this is the same specimen shown in these photographs?
This stone is recorded under serial TC-00018. Its specimen record is a permanent page holding the classification data as published in the Meteoritical Bulletin, the recorded weight, and photographs of this exact stone. Meteorite surfaces, cut faces and clast patterns are individual to each stone, so a specimen in hand can be compared against those photographs and weighed against the recorded figure.

Collector significance

Rumuruti chondrites are among the least common chondrite groups, and a main mass with documented fusion crust and two visible lithologies is a specimen with both scientific and display value. The Meteoritical Bulletin lists Sinawan 005 as one of three approved meteorites classified as R5-6, a verifiable count that reflects how few specimens of this exact classification exist. This piece is the main mass of Sinawan 005, held by Treasure Coast Meteorite Co., IMCA Member #3323, who submitted the stone for classification and retains it as sole owner.

Classification and provenance for this specimen follow the official Meteoritical Bulletin entry for Sinawan 005, viewable at the Meteoritical Bulletin Database.

Specimen record

This specimen is serialized as TC-00018 and is issued with a certificate card bearing that serial. The serial indexes a permanent public record maintained by Treasure Coast Meteorite Co., and every issued serial is listed in the Specimen Registry.