Graphite with growth spirals from marbles from
Namib Grube, Wlotzkas Baken, western Namibia

For more information, see Rakovan & Jaszczak (2002) American Mineralogist 87, 17-24.

Differential Image Contrast (DIC) photographs of spirals on the
(001) surfaces of two graphite crystals. Note the regularity of 120-degree
"notches" near the corners of the macrospiral steps, and in a few places,
60-degree notches at the edges of the steps.
John A. Jaszczak collection and photo.

Atomic Force Microscope (AFM) image of growth hillocks and
curious 120-degree and 60-degree "notches"
near the edges and corners of macrospiral steps.
John Rakovan collection and photo.

AFM images of fundamental screw-dislocation-generated growth spirals
which occur on the growth hillocks above. Most of the step edges are
6.7 Angstroms high (graphite's unit cell height along [001]), corresponding
to a "double step". Arrows point to 3.3 Angstrom steps, which
correspond to a single [001] d-spacing.
John Rakovan collection and photo.

Click on image above to find out: What does it all mean?

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