Carbonaceous chondrites that were seen to fall

NASA’s Meteorite Landings dataset (records to 2013) lists 44 carbonaceous chondrite falls, 4.1 % of all observed falls. The heaviest by far is Allende, which fell in Mexico in 1969 and recovered 2 tonnes; it is also one of the three heaviest falls of any kind. The most common group among them is CM, with 15 falls.

Every carbonaceous fall, oldest first

The table lists all 44. Many of the group names come from these falls: a group is named after a well-studied reference meteorite, so Mighei gives CM, Vigarano gives CV, Ornans gives CO, Renazzo gives CR and Karoonda gives CK.

Groups

CI falls are the rarest major group, with 5: Alais (1806), Orgueil (1864), Tonk (1911), Ivuna (1938), Revelstoke (1965). CI and CM rocks carry types 1 and 2, the most water-altered textures. CV and CO falls are type 3. Labels like C2-ung mark rocks that do not fit any group; Tagish Lake in Canada is one of them.

Small stones, a few giants

The median carbonaceous fall recovered 2.5 kg, a little under the median for all falls. Carbonaceous rock is soft and breaks easily, so many falls leave small fragments: Revelstoke (1 g), Tonk (7.7 g), Maribo (26 g) are the smallest recoveries in the group. Only four falls recovered 100 kg or more: Allende (CV3, 2 tonnes), Kainsaz (CO3.2, 200 kg), Murchison (CM2, 100 kg), Gujba (CBa, 100 kg).

Decade by decade

The chart shows no steady rise: carbonaceous falls arrive in ones and twos, with the 1930s as the only decade above five.

Heaviest in their country

In one country with three or more falls, the heaviest fall on record is carbonaceous: Allende in Mexico.

The CI falls by mass

The five CI falls differ widely in what was recovered: Orgueil 14 kg, Alais 6 kg, Ivuna 705 g, Tonk 7.7 g, Revelstoke 1 g. The largest, Orgueil, recovered more than all the other CI falls together, and the smallest left a single gram.

Groups compared

Within the carbonaceous family the groups differ in typical size. The table gives the median recovered mass and the heaviest fall of every group with at least three falls.

Scattered across the map

Carbonaceous falls rarely have a carbonaceous neighbour. For five of the 44 the nearest recorded fall is also carbonaceous; for all the others it is an ordinary chondrite or another kind of rock. The median distance from a carbonaceous fall to its nearest neighbour of any kind is 97 km, which reflects where it fell more than what it is made of.

First and latest of each group

Each carbonaceous group has its own history in the record. The table gives the earliest and the most recent fall of every group.

Several groups have no fall after 2000 in the record at all, which is a reminder of how few falls each group gets in a century.

Where the mass sits

All carbonaceous falls together recovered 2.6 tonnes. Allende alone holds 77 % of it, and the other 43 falls together recovered 614 kg. Only six falls in the group passed 20 kg, so a single large event decides most of the family’s total.

When and where

The oldest carbonaceous fall in the record is Alais in France (1806); the most recent is Sutter's Mill in the United States (2012). Of the 44, 17 fell in 1950 or later. The United States has the most (6), followed by France and India with 4 each.

Compared with finds, carbonaceous falls are a small set: the dataset holds 737 complete carbonaceous find records, with a median mass of 21 g. A fall of this soft, water-bearing rock is collected before rain and soil can alter it, which is one reason witnessed carbonaceous falls are studied so closely.

Small recoveries are common

Of the carbonaceous falls, 39 % recovered less than a kilogram, against 30 % of all falls. In the strip below, every fall in the record is a grey tick and the carbonaceous falls are dark; they spread across almost the whole range, from one gram to two tonnes.

The CM2 falls

All 15 CM falls in the record are type 2. In date order they are Cold Bokkeveld (1838), Nogoya (1879), Mighei (1889), Nawapali (1890), Haripura (1921), Boriskino (1930), Banten (1933), Crescent (1936), Santa Cruz (1939), Erakot (1940), Pollen (1942), Murray (1950), Murchison (1969), Sayama (1986) and Maribo (2009). Only Murchison recovered more than 20 kg.

By decade, the 1930s hold the most carbonaceous falls, 7. By continent, Europe has 14, Asia 11 and North America 10.

Where to go next

The carbonaceous chondrites page maps every fall in the group and charts them by decade. For what the letters and digits mean across all classes, read the note on class labels. To see whether a carbonaceous fall was recorded near you, open What fell near.