First Order of the Olivine Basalts.
Characters.—Olivine in abundance. Felspars of the groundmass
not in flow-arrangement.
Formula.—Oliv., matr., cop., non-flu.
| Sub-order. | Section. | Genus. | Species. | Number of specimens. | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pyroxene of the groundmass. | Presence or absence of plagioclase phenocrysts. | Character of the phenocrysts. | Length of felspar lathes. | |||||||||
| 1. Granular (gran.) | 1. Plagioclase phenocrysts (phen.) | 1. Glassy plagioclase phenocrysts (vitr.) | ·02-·1 mm. | 1 | ||||||||
| ·1-·2 " | 2 | |||||||||||
| ·2-·3 " | ||||||||||||
| ·3-·5 " | ||||||||||||
| 2. Opaque plagioclase phenocrysts (opac.) | ·02-·1 mm. | |||||||||||
| ·1-·2 " | 1 | |||||||||||
| ·2-·3 " | 2 | |||||||||||
| ·3-·5 " | ||||||||||||
| 2. No plagioclase phenocrysts (non-phen.) | 3. Large phenocrysts of olivine and pyroxene, over 2 mm. (magn.) | ·02-·1 mm. | ||||||||||
| ·1-·2 " | ||||||||||||
| ·2-·3 " | ||||||||||||
| ·3-·5 " | 1 | |||||||||||
| 4. Small phenocrysts of olivine and pyroxene under 2 mm. Pyroxene scanty and often absent (parv.) | ·02-·1 mm. | |||||||||||
| ·1-·2 " | ||||||||||||
| ·2-·3 " | ||||||||||||
| ·3-·5 " | 1 | |||||||||||
| 2. Prismatic (prism.) | 3. Phen. | 5. Vitr. | ||||||||||
| 6. Opac. | ||||||||||||
| Not represented. | ||||||||||||
| 4. Non-phen. | 7. Magn. | |||||||||||
| 8. Parv. | ||||||||||||
| 3. Ophitic (oph.) | 5. Phen. | 9. Vitr. | Not represented. | |||||||||
| 10. Opac. | ||||||||||||
| 6. Non-phen. | 11. Magn. | Not represented. | ||||||||||
| 12. Parv. | ·1-·2 mm. | 1 | ||||||||||