Grouplet · Stony meteorites › Chondrites

K chondrites (Kakangari grouplet)

A tiny grouplet with a mix of features found in no other chondrite group.

Classification: Stony meteorites › Chondrites › K chondrites (Kakangari grouplet)
Share of witnessed falls: about 0.1%
In our catalogue: 3 meteorites, 1 seen to fall
Heaviest: Kakangari, 350 g
Earliest recorded fall: Kakangari, 1890
Type specimen: Kakangari, fell in India in 1890

K chondrites are named after Kakangari in India, which fell in 1890. With fewer than five known members, they are a grouplet rather than a full group. They have a mixture of features, including a matrix with the chemistry of enstatite and an oxidation state between ordinary and enstatite chondrites, which shows they come from a separate parent body.

Mineralogy and chemistry

K chondrites have an unusual recipe. Fine-grained matrix makes up most of the rock, around 70% or more, yet that matrix is made largely of magnesium-rich enstatite and olivine rather than the iron-rich dust of carbonaceous chondrites. Metal makes up about 6% to 10%, and chondrules about a quarter. Olivine has only about 2–4 mol% fayalite, so they are more reduced than ordinary chondrites but more oxidised than enstatite chondrites.

Their oxygen isotopes plot below the terrestrial line, near the field of the CR chondrites, while their mineral chemistry is closer to enstatite and ordinary chondrites. No other group combines these features.

Parent body and formation

Because their combination of chemistry and isotopes is unique, K chondrites must come from a parent body of their own. They are all type 3, so they were never strongly heated, and they show little sign of alteration by water. Their matrix may be an unusual mix of dust that condensed or was processed under reducing conditions. With so few samples, their parent body and where it formed remain a puzzle.

Abundance, type specimen and examples

Kakangari, the type specimen, fell in southern India on 4 June 1890, and only about 350 g survives, shared among a few collections. A handful of finds share its features, including Lewis Cliff 87232 from Antarctica and Lea County 002 from New Mexico. With fewer than five clear members, the K chondrites remain a grouplet rather than a full group; five unpaired members are needed for group status.

Why they matter

K chondrites show that the chondrite groups do not neatly fill all possible combinations of chemistry and isotopes. A body that formed in an unusual corner of the early Solar System can leave only a handful of samples on Earth. Each new grouplet like this widens the count of separate parent bodies sampled by meteorites, and shows that the asteroid belt once held many more kinds of primitive bodies than the main groups suggest.

Kakangari was treated as a lone oddity for about a century. Only in the mid-1990s, once Antarctic and American finds were shown to share its unusual matrix, mineral chemistry and oxygen isotopes, was it recognised as the first member of a grouplet named after it.

How to recognise one

Specimens are small and look like dark, fine-grained chondrites with small chondrules and some metal. Nothing about their appearance sets them apart: only detailed mineral analysis and oxygen isotope measurements can identify a K chondrite, so new members are most likely to emerge from the steady classification of desert and Antarctic finds.

Famous examples

Kakangari K3, India, 1890 · 350 g
Lewis Cliff 87232 K, Antarctica, 1987 · 23 g
Lea County 002 K3, United States, 1988 · 11 g

Related groups

Enstatite chondrites Chondrites formed with almost no oxygen to spare, full of rare minerals unknown on Earth's surface.
CR chondrites Metal-bearing carbonaceous chondrites with some of the most pristine organic matter known.
Chondrites Primitive stones that never melted, made of the first solids of the Solar System. The most common meteorites of all.

See all 3 K chondrites (Kakangari grouplet)

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