Gujba

Pressure leaves
a record.

CBA CHONDRITE

A micro-Raman investigation into shock metamorphism and high-pressure mineral transformations within the Gujba meteorite.

Metal-rich material surrounding prominent chondrules in the specimen reproduced in the Gujba poster. — The Gujba specimen10 mm bar in original

01 / THE QUESTION

One meteorite.
Different histories?

Gujba is a CBa chondrite, distinguished by high metal content, large metallic clasts, and barred olivine chondrules. Its minerals preserve evidence of shock metamorphism.

The study asks which high-pressure phases occur, what pressure ranges they suggest, and how the record varies across the sample.

A Raman phase map superimposed on the optical image, reproduced from the poster. — Mineral phases in context90 μm bar in original

How the Raman investigation was carried out

Three sample regions were examined using a WiTec Alpha 500R confocal Raman microscope at the American Museum of Natural History. The poster specifies a 50× objective, 532 nm laser, 5 mW power, and a 300 grooves/mm grating.

Raman spectroscopy provides evidence for mineral structures; mapping places that evidence within the observed textures.

↗ Gujba poster · methods

02 / THREE REGIONS

Pressure is
not uniform.

Different mineral assemblages underlie the poster’s pressure estimates. Explore each region to separate what was observed from how it was interpreted.

REGION 01

Large barred olivine chondrule

16–18GPa · estimated

05101520 GPa

OBSERVATION

Both brittle and plastic deformation are reported in this region.

REPORTED MINERALS

Olivine / Enstatite / Minor majorite

INTERPRETATION

The poster interprets the deformation and mineral assemblage as evidence of a shock regime of approximately 16–18 GPa.

The original stacked spectra reproduced in Figure 2 of the research poster. — Gujba Raman spectral overlaysRaman shift in cm⁻¹; original axes retained

Contextual evidence from the Gujba poster. Its captions do not explicitly register these spectra to each numbered region.

03 / MICROMETERS

Look at the texture.
Then the signal.

Reflected light shows the structure. An analytical overlay adds spatial information. Move the divider to compare the paired views without changing the original image colors.

REFLECTED LIGHTANALYTICAL OVERLAY

Area 2 reflected-light microscopy with original scale bar

Area 2 registered RGB analytical overlay with original scale bar

Drag to compare50% reflected light

60 μm original scale bar · zoomed views pan by dragging or scrolling

Area 2 visually matches Gujba poster Figure 2. It is not a verified Sahara 97037 field or a numbered-region assignment.

04 / READING THE RECORD

A localized record
of extreme pressure.

What the study concludes

Wadsleyite is localized and majorite is distributed inconsistently. Together with the reported clinoenstatite, these findings support heterogeneous shock effects at microscopic scales.

The poster estimates approximately 8–12 GPa in the fine-grained matrix, 16–18 GPa in the large barred chondrule, and 18–20 GPa in the chondrule fragment and adjacent matrix.

What the evidence means

The project reports clinoenstatite in Gujba for the first time in this research context. This is presented as the poster’s claim, without implying a supplied peer-reviewed publication.

The scientific value lies in relating mineral transformations to their spatial setting: different parts of one sample can preserve different conditions from its shock history.

THE RESEARCH, IN FULL