Impact Melt Meteorites & Shock Ratings

Impact Melt Meteorites or Impact Melt Breccias (IMB) have formed from material that was liquefied or partially liquefied from the extreme pressure and heat generated by a large meteorite or asteroid impact in space. When two bodies in space collide with enough force (due to their mass and velocity) they create massive instantaneous pressures. Depending on the pressure it will affect these meteoroids (later to become meteorites) in different ways. More lightly shocked meteorites may just display dark shock veins running through while the Impact Melts will display a melted and deformed matrix. The information below is derived from studies presented by D. Stöffler et al. (1991).

Meteorites are given a shock rating when they are classified. The scale works from 1 (unshocked) right up to 6 (very strongly shocked). These pressures are given values in GPa. 1 GPa is equal to 10,000 bars or in other words about 5,000 times the pressure of a car tyre! Below is a table outlining the Stöffler Shock Rating system.

Unclassified Saharan Impact Melt - 13.70g Half-Stone

NWA 2085 (L-Impact Melt) - 96g Slice

NWA 540 (H6 Impact Melt)

NWA 540 (H6 Impact Melt) - Close-up Image

Cat Mountain (L5 Impact Melt)

Rammya (H5 Impact Melt)

Return to Odds/Ends & Trivia home...