Chelyabinsk (LL5)

Chelyabinsk is perhaps the most famous observed meteorite fall in recent times. On the morning of Feburary 15th 2013, a large fireball was observed streaking across the Russian sky, where it exploded and fell to the ground over the Chelyabinsk district. The explosion shook nearby towns and shattered many windows throughout the region. Thousands of stones showered down to the snow covered ground. One large mass penetrated the ice of Lake Chebarkul and was recovered by divers from the muddy bottom on October 16th 2015. It weighted upwards of 570 kg and is the main mass of the fall.  Several other pieces have been recovered from the lake since the massive find.

Stones feature fresh black fusion crust and a typical LL5 light matrix containing shock veins. Some (fresh) stones have a brownish fusion crust. Additional samples have shown that a portion of the stones consist of fine grained black impact melt.

Petrography as follows: (D.D. Badyukov and M.A. Nazarov, Vernad). The majority (2/3) of the stones are composed of a light-colored lithology with a typical chondritic texture. Chondrules (~63%) are readily delineated and set within a fragmental matrix. The mean chondrule diameter is 0.93 mm. The chondrule glass is devitrified. The main phases are olivine and orthopyroxene. Olivine shows mosaicism and planar fractures. Rare grains of augite and clinobronzite are present. Small and rare feldspar grains show undulatory extinction, planar deformation features, and are partly isotropic. Troilite (4 vol.%) and FeNi metal (1.3 vol.%) occur as irregularly shaped grains. Accessory minerals are chromite, ilmenite, and Cl-apatite. A significant portion (1/3) of the stones consist of a dark, fine-grained impact melt containing mineral and chondrule fragments. Feldspar is well developed and practically isotropic. No high-pressure phases were found in the impact melt. There are black-colored thin shock veins in both light and dark lithologies. Direct link to Meteoritical Bulletin here.

 

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