Dong Ujimqin Qi meteorite, East Ujimqin Banner (Dongwuzhumuqin Co.; Dongwu Qi), Xilingol League (Xilinguole Prefecture), Inner Mongolia, Chinai

Regional Level Types
Dong Ujimqin Qi meteorite	Meteorite Fall Location
East Ujimqin Banner (Dongwuzhumuqin Co.; Dongwu Qi)	County
Xilingol League (Xilinguole Prefecture)	Prefecture
Inner Mongolia	Autonomous Region
China	Country

Mesosiderite (Stony-Iron)
Fall, 7 Sept 1995; 128 kg

On a cloudless day a tremendous sound was heard, black smoke was seen, and 3 meteorite masses with fusion crusts were soon recovered, the largest 88.2 kg. Dong Ujimqin Qi was only the 7th witnessed mesosiderite fall. Mesosiderites normally consist of approximately equal masses of once molten Fe-Ni metal which may have penetrated into a nearly equal mass of now heavily brecciated orthopyroxene-rich silicates. Other silicates (esp. olivine and plagioclase), troilite, chromite, and other minor constituents are found in Dong Ujimqin Qi (as in other mesosiderites). The Ca-poor, slitely variable pyroxene in Dong Ujimqin Qi is usually ~ 24 mol% ferrosilite; plagioclase appears to be mostly anorthite, and the olivine — often found in large crystals several cm in diameter — is unusually Mg-rich. Minor and even trace amounts of such minerals as merrillite, tridymite, and standfieldite is to be expected. The presence of cordierite is a little surprising as it is a metamorphic phase in terrestrial geological environments. Cordierite had, however, been found previously in the Chaunskij mesosiderite.

A number of active and still unresolved hypotheses are under discussion as to how the original mesosiderites were created on an ancient original parent body and/or during a collision between two asteroids. Much later, after presumably being separated from a mother asteroid or asteroidal fragment, Dong Ujimqin Qi experienced a relatively long cosmic exposure age of 250±50 Ma before it eventually collided with the earth.

Over 200 mesosiderites have been found, many of them small, weathered, and fragmented, in the cold and hot desserts of Antarctica, Australia, Africa, the Americas and elsewhere. A good number of them are moderately massive (28 with m> 10 kg by late 2014) and sometimes yield valuable info. However, the brecciated nature of the 'normal' mesosiderite makes them — and especially their sulfides and phosphides — particularly vulnerable to chemical attack in almost any terrestrial environment. Thus, Dong Ujimqin Qi, as the 2nd most massive mesosiderite fall and the 7th most massive mesosiderite overall, is a particularly valuable addition to the mesosiderite collection.

Other Regions, Features and Areas containing this locality

References