Metal in two CL chondrites

At this writing, September 2022, there are five CL, Loongana group, carbonaceous chondrites. All are of petrologic type 3.9 or 4.

Metzler et al. defined the group in 2021.
David Weir addresses the subject well on his Coolidge page.

CL chondrites contain as much metal as do CR2 chondrites. Here are samples of two CL chondrites showing metal inside chondrules, on chondrule rims and in their matrix.

Coolidge CL4. This was a thick slice which I had “butterflied” with one portion thin sectioned and this portion polished on both sides.

Metal shows well with oblique lighting.

Under a microscope in reflected light the metal is bright white. Metal is inside the central chondrule, around its rim and in the surrounding matrix. Portions of other armored chondrules appear below and to the left. Coolidge CL4. Field of view is 3.6mm wide.

Adjacent chondrules, armored with metal on left and metal within on right. Coolidge CL4. FOV=2.3mm.

Central metal bleb surrounded by troilite. Coolidge CL4. FOV=2.3mm.

NWA 13400 CL3.9, 2.026 gram slice from Mirko Graul.

NWA 13400 CL3.9 thin section by David Mann.

NWA 13400 CL3.9 thin section in transmitted light.

NWA 13400 CL3.9 thin section in oblique reflected light to show metal.

In reflected light, metal and troilite appear inside a chondrule and surroundings. Terrestrial weathering has produced veins and altered some metal. NWA 13400 CL3.9. Field of view is 2.3mm wide.

Incident light view of area above plus a little more.

Armored chondrule in reflected light. NWA 13400 CL3.9. Field of view is 2.3mm wide.

Same chondrule as above. Cross-polarized light. NWA 13400 CL3.9.

John Kashuba

John is a natural history enthusiast living in Oregon.