Fibrils Mistaken for Saponite/Serpentine? A Comparison of Ryugu and Terrestrial Wood Nanostructures

All articles by Wretch Fossil are here: http://www.wretch.cc/blog/lin440315&category_id=0

Author: ChatGPT/Liangtai Lin

Introduction

Recent high-resolution transmission electron microscopy (TEM) images from asteroid Ryugu samples have reignited the debate about possible biological templating in extraterrestrial material. One key point of contention lies in the interpretation of nanofibrillar structures: are they biogenic remnants or merely mineral growths like saponite or serpentine? This article presents a side-by-side comparison between TEM-imaged fibrils from Earthly Kraft pulp wood and those observed in Ryugu samples, highlighting their structural similarities.

Comparative Image Analysis

Figure 1. TEM image of a spruce Kraft pulp fiber surface replica, showing the microfibril orientation. Red rectangles mark distinct fibrils. The original scale bar indicates 100 nm. (Adapted from Duchesne and Daniel, 1999, enlarged 800% for clarity)

Both figures show:
– Alignment: Fibrils in both images appear bundled and oriented along preferred directions.
– Segmented Texture: Some fibrils show internal banding or modular segments.
– Diameter Range: Observed widths range from ~3–5 nm for elementary fibrils, bundling up to ~100 nm.

Biological Interpretation

The fibrils in Figure 1 are confirmed cellulose microfibrils derived from vascular plant material. Their morphology—thread-like, flexible, and segmented—provides a valuable analog for interpreting the Ryugu structures.

The image from Ryugu (Figure 2) contains:
– Cylindrical nanostructures bundled into aligned arrays.
– Size and morphology closely matching that of terrestrial microfibrils.
– No crystalline boundaries indicative of mineral precipitation.

This raises the question: Could these asteroid structures originate from fossilized or templated organic matter rather than from inorganic crystallization?

Abiotic Counterarguments

Advocates for a mineral origin argue:
– The lattice spacings match known phyllosilicates.
– Aqueous alteration on Ryugu could yield fibrous clay minerals.

However, these arguments do not explain:
– The bundling and consistent orientation of fibrils.
– The lack of mineral matrix continuity between fibrils.
– The hierarchical, multi-scale organization.

Conclusion

The resemblance between wood-derived cellulose fibrils and the fibrillar nanostructures in Ryugu material is striking. While further analytical chemistry is required for confirmation, current visual and morphological evidence supports the hypothesis that some structures on Ryugu may result from biological templating—challenging the purely mineralogical interpretation.

References

1. Duchesne, I. & Daniel, G. (1999). TEM imaging of spruce Kraft pulp fiber surface. In: Transmission Electron Microscopy for Wood and Fiber Analysis – A Review. https://www.researchgate.net/publication/280357003

2. Noguchi, T., et al. (2022). Formation and alteration history of carbonaceous asteroid Ryugu. Nature Astronomy, 6(8), 1009–1017. https://doi.org/10.1038/s41550-022-01745-5

Figure Credits:

Figure 1: Adapted from Duchesne & Daniel (1999), annotated and enlarged by the author.
Figure 2: From Noguchi et al. (2022), annotated by the author.

Wretch Fossil’s website:http://wretchfossil.blogspot.com/

Source: https://wretchfossil.blogspot.com/2025/08/fibrils-mistaken-for-saponiteserpentine.html