Most meteorites that have fallen to the Earth (~93%) are chondrites or achondrites (stony meteorites). A smaller fraction of them are iron meteorites (~6%), or pallasites and mesosiderites (stony-iron meteorites; ~1%) (4).
A statistical study of the rates of meteorite falls (5) suggests approximately 17 meteorites >0.1 kilograms (0.22 pounds) in size fall in Arizona, or an area of equal size, each year. Two to three of these samples weigh >1 kilograms (2.2 pounds) and are about the size of your fist. A meteorite weighing >10 kilograms (22 pounds) falls every 2 to 3 years. Thus, from the turn of the century, approximately 240 meteorites >1 kilograms in size are believed to have fallen in Arizona. Since Father Kino first arrived in the Tucson area (1687), approximately 790 meteorites >1 kilograms in size are believed to have fallen in Arizona. Of this large number of meteorites, only 32 have been recovered, and only 1 of these (the Holbrook meteorite) was observed to fall (2).
In comparison, 153 meteorites have been found in New Mexico, 3 of which were observed falling. Seventy of these samples were collected within Roosevelt County, where a special set of circumstances has preserved and concentrated a large number of meteorites.
It should be clear from these numbers that most meteorites that fall are not found, and very few are actually observed hitting the ground. Thus, there are many meteorites in Arizona waiting for some curious soul to take notice.
|Canyon Diablo||Coconino||Iron||Found 1891|
|Cat Mountain||Pima||OC||Found 1980-82|
|Cave Creek||Santa Cruz||OC||Found 1992|
|Clover Springs||Gila||MES||Found 1954|
|Coon Butte||Coconino||OC||Found 1905|
|El Mirage||Maricopa||Iron||Found 1972|
|Gold Basin||Mohave||OC||Found 1995|
|Gun Creek||Gila||Iron||Found 1909|
|Pima County||Pima||Iron||Found 1947†|
|Ryan Field||Pima||OC||Found 1982|
|San Francisco Mtns||Coconino?||Iron||Found ~1920|
|Silver Bell||Pima||Iron||Found 1939†|
|Southern Arizona||?||Iron||Found 1947|
|Snyder Hill||Pima||OC||Found 1994|
|Udall Park||Pima||OC||Found 1985|
|Weaver Mtns||Maricopa||Iron||Found 1898|
|Willcox Playa||Cochise||OC||Found 1979|
* CC = carbonaceous chondrite, OC = ordinary chondrite, EC =
enstatite chondrite, MES = mesosiderite, AC = unusual
(4) Harvey and Cassidy (1989) Meteoritics, v. 24, pp. 9-14.
(5) Halliday and others (1989) Meteoritics, v. 24, pp. 173-178.
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