| Text Description: |
Block from the upper part of the carapace of Dome F at Site 4. Fine grained, holocrystalline, porphyritic with a matrix of equigranular feldspar, quartz, opaque and alteration. Plagioclase phenocrysts (An31 - An45) are up to 2.95 mm and tend to be rounded, frequently have strong oscillatory zoning and some mica alteration is present. Opaque phenocrysts are up to 0.45 mm. There is an altered phase that now consists of opaque rim with granular core of an unidentifiable high relief mineral ± feldspar. A second altered phase, larger in size, is now serpentine/chlorite. 82.0% matrix, 14.7% plagioclase, 0.2% opaque, 0.6% altered phase, 0.2% alteration, 2.3% vesicles. |