Meteorite fall statistics

Meteorite fall statistics are frequently used by planetary scientists to approximate the true flux of meteorites on the Earth. Meteorite falls are those meteorites that are collected after being witnessed to fall, whereas meteorite finds are discovered at a later time. Although there are 30x more finds than falls, their raw distribution of types does not accurately reflect what falls to Earth. The reasons for this include:

1. Some meteorite types are easier to find than others
2. Some meteorite types are degraded by weathering more quickly than others
3. Some meteorites, especially iron meteorites, may have been collected by people in the past who recognized them as being unusual and/or useful, thereby removing them from the scientific record
4. Many meteorites fall as showers of many stones, but when they are collected long after the event it may be difficult to tell which ones were part of the same fall
5. Many meteorites are found by people who sell meteorites... valuable, rare types become known to science quickly, while those of low value may never be described.

There have been many attempts to correct statistical analyses of meteorite finds for some of these effects, especially to estimate the frequency with which rare meteorite types fall. For example there are over 100 known lunar meteorite finds, but none has ever been observed to fall. However, for abundant types, meteorite fall statistics are generally preferred.

These statistics are current through June 27, 2011.

Statistics by material

For most meteorite falls, even those that occurred long ago or for which material has never received complete scientific characterization, it is known whether the object was a stone, stony iron, or iron meteorite. Here are the numbers and percentages of each type, based on literature data^[1][2][3].

Material	Number	%
Iron meteorites	49	4.5%
Stony-iron meteorites	11	1.0%
Stony meteorites	1036	94.5%
Total	1096	100.0%

Statistics by major category

The traditional way of subdividing meteorites (see Meteorites classification) is into irons, stony-irons, and two major groups of stony meteorites, chondrites and achondrites. For some of the less-studied stony meteorite falls, it is not known whether the object is chondritic; thus the number of meteorites that can be so grouped is 4% lower than shown above. These numbers are shown in the next table. One could make a slight correction for the undercounting of stony meteorites (e.g., the percentage of irons would decrease by a 0.2%), but this was not done.

Category	Number	%
Irons	49	4.6%
Stony irons	11	1.0%
Achondrites	85	8.1%
Chondrites	910	86.3%
Total	1055	100.0%

Statistics by meteorite group

Probably the most useful statistical breakdown of meteorite falls is by group, which is the fundamental way that meteorites are classified. About 5% of the meteorites in the table just above have not been sufficiently classified to allow them to be put into such groups. Again, a small adjustment could be made to the percentages to correct for this effect, but it does not greatly change the results. Note that a number of meteorite groups are only represented by a small number of falls; the percentages of falls belonging to these groups have a large uncertainty.

Group N % Iron meteorites IAB complex 10 1.0% IC 0 0.0% IIAB 6 0.6% IIC 0 0.0% IID 3 0.3% IIE 2 0.2% IIF 1 0.1% IIG 0 0.0% IIIAB 11 1.1% IIIE 0 0.0% IIIF 0 0.0% IVA 4 0.4% IVB 0 0.0% Ungrouped 4 0.4% Stony Iron meteorites Mesosiderite 7 0.7% Pallasite 4 0.4%	Group N % Achondrites Acapulcoite 1 0.1% Lodranite 1 0.1% Angrite 1 0.1% Aubrite 9 0.9% Diogenite 11 1.2% Eucrite 34 3.5% Howardite 16 1.6% Brachinite 0 0.0% Ureilite 6 0.6% Winonaite 1 0.1% Ungrouped 1 0.1% Lunar 0 0.0% Martian 4 0.4%	Group N % Class total Chondrites CB 1 0.1% Carbonaceous: 4.3% CH 0 0.0% CI 5 0.5% CK 2 0.2% CM 15 1.5% CO 6 0.6% CR 2 0.2% CV 7 0.7% C ungrouped 5 0.5% EH 8 0.8% Enstatite: 1.6% EL 8 0.8% H 338 34.0% Ordinary: 80.1% H/L 1 0.1% L 369 37.1% L/LL 9 0.9% LL 81 8.1% R 1 0.1% Other: 0.2% K 1 0.1%
Grand Total: 996 meteorites

Statistics by Country

Country N Afghanistan 1 Algeria 7 Angola 3 Argentina 24 Armenia 2 Australia 16 Austria 4 Azerbaijan 2 Bangladesh 8 Belarus 3 Belgium 3 Bosnia and Herzegovina 1 Brazil 22 Bulgaria 5 Burkina Faso 8 Burma 3 Cambodia 2 Cameroon 3 Canada 16 Central African Republic 1 Chad 1 Chile 1 China 57 Colombia 1 Congo - Dem. Rep. 5 Costa Rica 1 Croatia 4	Country N Czech Republic 15 Denmark 4 Ecuador 1 Egypt 2 Estonia 3 Ethiopia 5 Finland 5 France 63 Germany 32 Ghana 1 Greece 1 Hungary 6 India 127 Indonesia 16 Iran 2 Iraq 2 Ireland 6 Italy 31 Japan 42 Jordan 1 Kazakhstan 6 Kenya 3 Latvia 4 Lebanon 1 Lesotho 1 Libya 1 Lithuania 4 Madagascar 1	Country N Malawi 5 Mali 2 Mauritania 3 Mauritius 1 Mexico 19 Mongolia 4 Morocco 5 Namibia 2 Netherlands 4 New Caledonia 1 New Zealand 1 Niger 9 Nigeria 14 Norway 9 Pakistan 15 Papua New Guinea 2 Paraguay 1 Peru 1 Philippines 4 Poland 10 Portugal 6 Romania 7 Russia 47 Rwanda 1 Saudi Arabia 4 Serbia 4 Slovakia 3	Country N Slovenia 2 Somalia 2 South Africa 21 South Korea 3 South Sudan 3 Spain 23 Sri Lanka 1 Sudan 7 Swaziland 1 Sweden 9 Switzerland 4 Syria 1 Tanzania 8 Thailand 3 Tunisia 5 Turkey 12 Turkmenistan 2 Uganda 5 Ukraine 32 United Kingdom 18 United States 145 Uzbekistan 2 Venezuela 2 Vietnam 3 Western Sahara 3 Yemen 2 Zambia 1 Zimbabwe 2
Grand Total: 1096 meteorites

Statistics by Continent and Time

Epoch	Europe	Asia	North America	Africa	South America	Oceania	Total
Pre-1400	1	1					2
15th century	4						4
16th century	2						2
17th century	9	3					12
18th century	25	3					28
1800–1820	31	7	3	1			42
1821–1840	26	11	9	1	1		48
1841–1860	42	15	12	1			70
1861–1880	47	36	14	6	4	1	108
1881–1900	36	27	20	7		2	92
1901–1920	26	55	21	10	4	2	118
1921–1940	38	55	32	17	14	5	161
1941–1960	27	27	18	31	12	3	118
1961–1980	19	42	22	29	8	3	123
1981–2000	12	49	19	24	4	2	110
2001-	10	14	11	15	6	2	58
Total	355	345	181	142	53	20	1096

References

1. ^ Meteoritical Bulletin Database
2. ^ The NHM Catalogue of Meteorites
3. ^ MetBase