Hola Chuck,
Yes, I like Type 3 chondrites but I don’t think I said they were pristine. Maybe you heard someone else say that. I think I said they are the least changed by heat and water. I admit that I was being careful with my wording because I know that some chondrites that the smart people tell us are Type 3 still have had a tough life. I’ve got a couple in mind that have been worked over pretty good.
One, Korra Korrabes an H3 from Namibia, is brecciated. I wouldn’t call that pristine. But its shock level is still only S1. And it gets the 3 rating because the glass in the chondrules has not crystallize much at all. This means that it hasn’t been seriously affected by heat. I got some thin sections and some hand specimens from Ronnie Mckenzie at the Denver show. Denver is the only show he does as a dealer. He’s an engineer, meteorite enthusiast and generally good guy from South Africa.
Maybe the light colored clasts got mixed in gently, early on while the asteroid was coming together so no shock was needed for the brecciation. Just guessing. Look at the pictures then tell me what you think.
– John
About 20% of Korra Korrabes is light colored clasts. That shows pretty well in this slice.
Some of the clasts are angular and show up well in thin sections viewed in crossed polarized transmitted light.
The main H3 lithology is on the left
Both lithologies have interesting features.
NWA 2911 is an L3.5. That qualifies as a Type 3 doesn’t it? These thin section pictures show that life hasn’t been easy for this rock either.
This meteorite is full of cracked and broken chondrules, mineral grains and clasts.
Some chondrules contain relict grains. This thing’s been reworked a good bit.
Check out the radial pyroxene chondrules. They’ve been bleached a little around the edges – the work of water back home on the asteroid. The big gray one on the left was broken then bleached. The brown one on the bottom right was bleached then broken.
John may be reached at john(at)johnkashuba.com
