| Orthoclase occurred as remnant phenocrysts in a groundmass of chloritic material resulting from alteration of iron-rich felsite cobbles. |
| The highly fractured felsite is cemented by veinlets of chrysocolla and malachite with minor amounts of cuprite. |
| We found, besides, a few cores of felsite and some shapeless flakes and several fragments of large metates. |
| In the south of the island there are sills and dykes of felsite, quartz-porphyry, rhyolite, trachyte and pitchstone. |
| The sedimentary beds are composed mainly of poorly sorted subangular to rounded clasts of felsite and rhyolite porphyry that are typically a red color. |
| Still later, dolerite sills and sheets and dikes of granophyre and quartz felsite followed in the same region. |
