These Depressions Are Not Meteorite Regmaglypts

Regmaglypts NOT

All the photos below were sent to me by people who thought the rocks had regmaglypts. None of these rocks are meteorites – none has a fusion crust. Some terrestrial processes lead to rocks depressions that can look very much like meteorite regmaglypts. Many of these features are the result of sculpting by wind or water on Earth. Some of the depressions are incipient vesicles. Preferential weathering occurs when softer material weathers away before harder material. This process seems to occur most commonly in sedimentary rocks. Another process is “plucking” in which hard, rounded clasts fall out of a softer matrix leaving a rounded depression.

If there is no fusion crust, then the depression is not a regmaglypt.

The coating looks much like a meteorite fusion crust, but I think that it is just desert varnish. The shape is like that of a ventifact, so the pseudo regmaglypts were likely formed by wind sculpting.

I have seen photos several rocks that appear to be mostly quartz or calcite that has been preferentially etched by saline solutions leaving a regmaglypt-like surface. The light-colored rock at the top center of the mosaic above is a good example. (If someone knows more about this than me, please let me know.)

The rocks on the upper left and lower left are shiny, like a meteorite fusion crust, but I suspect that it is just a polish. I have no idea of what caused the geometric holes in the left rock in the center row. I think the dark areas on the rock to the right (middle row) are hard veins and the lighter host material has weathered away. The middle and right rocks on the bottom row have no fusion crusts.  

Geologist would described all of these rocks as “plucked” because the rounded clasts have been plucked (picked out and lost) from the stone, leaving a rounded cavity.