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Relict Grains

Chondrules were molten droplets.  What caused the melting is hotly debated  (har).  Chondrule textures reflect the extent of melting  and rates of cooling.  Porphyritic chondrules did not fully melt.  Fine-grained porphyritic chondrules began cooling with many fine  widely distributed  unmelted mineral crystals.  Coarse-grained porphyritic chondrules had fewer.  Either type can contain larger grains  that survived the melting episode and retain their original character.  Here are some chondrules with relict grains.

Relict grain right in the center.

Relict grain is a barred chondrule.


Notice the rounded edges of the huge grain.

Large grain surrounded by opaque material . . .

. . . black opaque material.

Maybe not really a relict grain.

But it certainly looks like the rest built up around it.

Relict grain and more opaque blebs.



About the Author

John is a natural history enthusiast living in Oregon.