NWA 13784 CV3-an

NWA 13784 CV3-an was brought to us by Hanno Strufe and Andreas Grünemeyer, described by Ansgar Greshake with oxygen isotopes by Karen Ziegler.

It appears to have been affected by both water and shock. Olivine grains are strongly zoned from their centers out. Undulatory extinction is evident in some chondrules. A set of subparallel fractures separate offset blocks. Multilayered chondrules are common. Opaque phases are said to be troilite and taenite.

Our slice contained a few large chondrules. The largest had been cut across a length of 8.7mm.

Chondrule overall length is 8.7mm. The length of the interior chondrule is 6.1mm.

A 3mm diameter porphyritic chondrule with at least two additional layers.

The above chondrule in plane polarized light.

This BO chondrule displays undulatory extinction when rotated between crossed polarizing filters.

Complex barred chondrule with additional layers at top of photo. Diameter is about 2mm.

The pink-red bars appear to continue into as many as four overgrowth layers. Could this have been epitaxial growth during episodes of vapor deposition?

A set of subparallel fractures separate offset blocks.

Fracture runs diagonally from top left. Cross-polarized light and incident light.

Fracture runs diagonally from top left. Cross-polarized light and incident light.

The center of this 3mm long chondrule is troilite and nickel-iron. Note brown staining. Cross-polarized light and incident light.

Center chondrule is similar to the one in the previous photo. XPL and incident light. FOV=3mm.

CAI are abundant in the thin sections made from our slice. FOV=3mm.

CAI, FOV=3mm.

CAI, FOV=3mm.

Olivine grains are strongly zoned. The alteration often makes its way into cracks. FOV=3mm wide.

FOV=3mm wide.

FOV=3mm wide.

FOV=3mm wide.

FOV=3mm wide.

Diameter is 0.33mm.

Diameter is 0.6mm.

FOV=0.35mm wide.

John Kashuba

John is a natural history enthusiast living in Oregon.