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.
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.
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.
5. Left: Small grain of kamacite and tetrataenite. 160X, FOV 0.7
6. Right: Kamacite shaped like tuning fork or horseshoe, with small
tetrataenite grain at lower left extremity. 80X, FOV 1.4 mm, PPL-RL.
7. Left: Ragged kamacite, part-altered to troilite, with small,
cracked chromite grain. 160X, FOV 0.7 mm, PPL-
8. Right: Pyroxene-rich chondrule flanked by metal and troilite.
40X, FOV 2.8 mm, PPL-RL.
File updated on 31 October 2001.