BGS mineralogy and petrology collection record
| Sample number | E61958; COLLNOMH1559; |
|---|---|
| Sample Donor | Howells,M.F. |
| Rock name | Not entered |
| Stratigraphy | Not entered |
| Comments | Fine grained acid tuff (? Rhy/tuff)--Thin section: comprises spherules of alkali-feldspar within a cryptocrystalline chalcedony-like groundmass--possible perlitic precursor. Quartz is not common, colour index < 40 suggesting andesitic composition |
| Locality details | E of Craig Lwyd |
| 50k map sheet | Barmouth (149) |
| Map reference | SN 6559 1109 |
| Year collected | Not entered |
| Bore name | Not applicable |
| Confidentiality | No restrictions |
Petrological thin sections
Links to high resolution images
Transition from XPL to PPL light
E61958
