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John Kashuba

John is a natural history enthusiast living in Oregon.

Mukundpura CM2

Mukundpura CM2

CM2 meteorites are regolith breccias. They’ve been through cycles of crushing and lithification at an asteroid surface. They are dark with opaque matrix and varying amounts of chondrules, olivine aggregates, CAI and mineral grains. This is a sample of a CM2 fall that is reported to have distinct lithologies. Our samples, whose early field name […]

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NWA 5000 Lunar Melt Veins

NWA 5000 Lunar Melt Veins

I was given thirteen NWA 5000 Lunar (feldspathic breccia) thin sections to photograph. Each section has melt rock that merits attention. In some it appears as small puddles but in most it appears as veins, some traversing the full width of the sample. Of course thin sections are just that – thin (virtually two dimensional) […]

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Tony Irving’s Martians

Tony Irving’s Martians

In conjunction with the Meteoritical Society’s annual meeting which, this year, will be held in Santa Fe New Mexico, Dr. Tony Irving of the University of Washington will lead a post-meeting workshop {http://metsoc2017-santafe.com/workshops} Saturday, July 29, 2017. The topic is Martian Meteorites Under the Microscope. Here are shots of some of the thin sections he […]

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NWA 2824 Diogenite

NWA 2824 Diogenite

Ted Bunch and other researchers have described many shock induced features in this odd diogenite. We found some to photograph in a few thin sections, all viewed in cross-polarized light. Brecciation is a common result of shock. The clasts in this polymict breccia have a variety of textures. Mechanical twinning, also called shock twinning, is […]

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NWA 2724 Eucrite

NWA 2724 Eucrite

The assembly of polymict eucrites is neither gentle nor precise. It involves magma, impact excavation and cycles of rock crushing, mixing, lithification and more crushing. Drs. Wittke and Bunch tell us that NWA 2724 contains both subophitic and cumulate textured rock and is therefore polymict. Here is a thin section that shows this nicely.   […]

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Another look at DaG 1040 CV3

Another look at DaG 1040 CV3

Five years ago we took a general look at DaG 1040 and last March the subject was its metal content. Recently I got to look at two new thin sections of this meteorite and I am intrigued again by its variety of features and textures. The first five photos below survey the striking difference between […]

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NWA 1685 LL4 Bessey’s BL

NWA 1685 LL4 Bessey’s BL

NWA 1685 LL4 is a handsome, interesting meteorite. Numerous stones were introduced in two releases by Dean Bessey and called BL. Individuals are glossy black on the outside and clearly brecciated on the inside. The brecciation is distinct because chondritic clasts differ in shock darkening, impact melt rock is featureless grey and many clasts are […]

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Tieschitz H/L3.6

Tieschitz H/L3.6

Tieschitz is interesting in thin section. In our sample, large and small chondrules are set apart by opaque matrix. Radial pyroxene and cryptocrystalline chondrules display aqueous alteration. One large chondrule contains several relict grains. We see chondrules that appear to be radial olivine darkened with fine included particles, probably amphiboles or other alteration products, and […]

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SaU 008 Martian shergottite

SaU 008 Martian shergottite

Sayh al Uhaymir 008 is one of the several pairings with SaU 005. These pairings have a total weigh of about 25 pounds. It is a Martian basaltic shergottite of a type sometimes called olivine-phyric. It is composed of olivine megacrysts in a finer grained groundmass of pigeonite and plagioclase. In these cross-polarized light (XPL) […]

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Micro Visions Ribbons

Micro Visions Ribbons

We’ve seen curtains of microscopic bubbles before in meteorite thin sections. Readers might remember some in Greg HupĂ©’s NWA 6704 ungrouped achondrite, third photo. Here are others in another ungrouped achondrite that are intriguing for a couple of reasons. They often occur in multiple parallel sheets and they are sometimes quite wavy like heavy drapery. […]

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Metal in DaG 1040 CV3

Metal in DaG 1040 CV3

Dar al Gani 1040 is from central Libya, found on a long limestone plateau at about 2,000 feet elevation. We’ve looked at DaG 1040 before and noted its friable matrix, varied chondrules and prominent metal. Here we’ll concentrate on the metal. All photos, except the first two, are of thin sections in incident light.

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Souslovo L4

Souslovo L4

Souslovo Timeline: 1966 – Fireball 1997 – Hay cart wheel chock 2002 – L4, S2,W0/1

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Amoeboid Olivine Aggregates

Amoeboid Olivine Aggregates

Amoeboid olivine aggregates are common millimeter size inclusions in carbonaceous chondrite meteorites. Some are amoeba shaped, some are more chondrule-like. Their textures and compositions are variable, too – some appear to be transitional between calcium-aluminum-rich inclusions and some transitional between chondrules. The olivine is the magnesium-rich end member, forsterite. It was formed not from a […]

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Micro Visions 3.00

Micro Visions 3.00

3.00 is a rarely given petrologic grade assigned to meteorites which experienced the lowest levels of thermal alteration on the parent body. (Aqueous alteration is another matter.) NWA 8276 L3.00 was assigned this grade based on laboratory tests and a study by Grossman and Brearley published in 2005. Among many findings the study’s authors showed […]

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Two IMR Inclusions in NWA 869

Two IMR Inclusions in NWA 869

About 1% of the volume of NWA 869 L3-6 is impact melt rock (IMR) according to Metzler et al. Their study tells us a lot about these highly variable fine grained inclusions we find in cut stones. Some IMR clasts include mineral and rock clasts, some do not. The crystallized fallback material is depleted in […]

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