The Yafa H5 chondrite

Visual Sample Catalogue

Eight small photomicrographs of Yafa provide an indication of the silicate and metal textures in this interesting chondrite. They are variously taken in plane-polarized or cross-polarized light (PPL / XP), transmitted or reflected-light illumination (TL / RL). In terms of classification, the petrologic class (H) was determined by electron microprobe analysis of mineral chemistry (olivine, pyroxene and kamacite compositions), the `metamorphic grade' (5) and degree of shock (S2) from the textural and microstructural details. The freshly-recovered fall shows a negligible degree of weathering.

Chondrules [40 kb] Fine-grained chondrule [35 kb]

1. Left: Fine-grained and composite, barred olivine chondrules with coarse olivine crystals in fine groundmass. 80X magnification, long-axis field-of-view roughly 1.4 mm, XP-TL.

2. Right: Very fine-grained chondrule flanked by metal and troilite. 80X, FOV 1.4 mm, PPL-TL.


Fusion crust [26 kb] kamacite and troilite [21 kb]
3. Left: Smooth appearance of the fusion crust, containing traces of troilite. Kamacite is visible in the granular interior of the stone. 80X, FOV 1.4 mm, PPL-RL.

4. Right: Small kamacite, extensively replaced by troilite. 160X, FOV 0.7 mm, PPL-RL.


Kamacite and tetrataenite [60 kb] Kamacite and tetrataenite [26 kb]
5. Left: Small grain of kamacite and tetrataenite. 160X, FOV 0.7 mm, PPL-RL.

6. Right: Kamacite shaped like tuning fork or horseshoe, with small tetrataenite grain at lower left extremity. 80X, FOV 1.4 mm, PPL-RL.



Kamacite, troilite and chromite [25 kb] Chondrule rimmed by metal and troilite [30 kb]
7. Left: Ragged kamacite, part-altered to troilite, with small, cracked chromite grain. 160X, FOV 0.7 mm, PPL- RL.

8. Right: Pyroxene-rich chondrule flanked by metal and troilite. 40X, FOV 2.8 mm, PPL-RL.



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File updated on 31 October 2001.