They are ideal for detailed studies because they are common, more impact-resistant than most other minerals and their composition and zoning can be easily studied. Being bulky, closely packed hexoctaedral nesosilicates garnets are rather stabile and resist rather high pressures. They are commonly the most intact impactite mineral phase if present in the original mineral assembly. Compared to other common rock-forming minerals of an impactite garnets have suffered of only minor mechanical fracturing. Their zoning makes, however, it rather difficult to find the exact amount of impact-influenced compositional effects.
Garnets look rather fresh and intact in the impactite rocks studied.
The original garnet composition reflects the high-T,P areal metamorphic environment. The FeO, MgO, MnO3 and CaO abundances in various garnets were analysed as point profiles from crystal edge to the centre. Abundance in the crystal centre was set to one unit. Barbs indicate possible diffusion direction. The exact numbers shown above represent only one sample but very similar analyses have also been obtained from samples from several other locations.