Shock vein
A shock vein is a thin, dark streak of rock that melted for an instant when a powerful impact shock wave passed through a meteorite's parent body.
When an asteroid is hit hard, the shock wave does not heat all the rock evenly. Along cracks, grain boundaries and weak zones, friction and pressure concentrate energy, melting thin sheets of rock in a split second. The melt quenches quickly into dark, fine-grained or glassy material, often carrying tiny droplets of metal and sulfide. These are shock veins, sometimes called shock-melt veins.
They are valuable records of collision. Because they form under high pressure and cool fast, shock veins can trap high-pressure minerals such as ringwoodite and majorite, letting scientists estimate how intense the impact was. Thick, abundant veins usually mean a high shock stage and often go with darkened, shock-blackened rock.
The Chelyabinsk LL5 chondrite, which exploded over Russia in 2013, has prominent black shock veins and shock-darkened material that made many of its fragments split along the veins. Tenham, an L6 chondrite that fell in Australia in 1879, is famous for ringwoodite in its veins. On a cut face, look for sharp black lines or networks crossing the interior. Unlike rusty weathering cracks, which are orange-brown, shock veins are black and contain melt.
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