Russian Meteor: Chelyabinsk Asteroid Had Violent Past

astroengine (1577233) writes "The asteroid that hit Earth last year and exploded over Chelyabinsk, Russia, had a prior crash record. Fragments of the asteroid recovered after the powerful Feb. 15, 2013, airburst show it contained an unusual form of the mineral jadeite embedded in glassy structures known as shock veins. Shock veins typically form when the parent body of a meteor or asteroid collides with a larger object in space. Heat and pressure from the impact cause rock to melt. It later reforms bearing vein-shaped patterns. 'Impact-induced jadeite has been found from other shocked meteorites. However, a unique point of the Chelyabinsk jadeite is that it seems to have crystallized from melt. To my knowledge, previously reported jadeite in other meteorites is considered to have formed (by solid-state reaction) without melting,' graduate student Shin Ozawa, with Japan's Tohoku University, wrote in an email to Discovery News."