The limited material recovered from Holes 1273A, 1273B, and 1273C is almost exclusively basalt. Three rounded pieces of serpentinized harzburgite were recovered from Hole 1273C. Most basalts look like sectors of pillows with a crust of fresh glass. A few pieces retain adhered hyaloclastite. The basalts are not deformed, display no structural features, and except for one (Section 209-1273A-1R-1 [Piece 9]), all pieces are small and nonoriented.
The basalts are predominantly aphyric with a few plagioclase phenocrysts dispersed in the matrix (<0.5%). Plagioclase crystals are as large as 5 mm in Section 209-1273C-1R-1 (Pieces 4, 8); 2 mm in Section 2R-1 (Piece 2); and 1 mm in Section 209-1273B-3R-1 (Piece 8). All of the basalts have 1%–8% vesicles with a maximum size of 1.5 mm. The vesicles are randomly distributed overall but slightly more abundant toward the rims of pieces interpreted to be pillow fragments. A sector of pillow basalt with variolitic structure toward the rim is in Section 209-1273B-3R-1 (Piece 8). Thin section examination reveals the basalts have a microcrystalline to intergranular texture (Sample 209-1273A-1R-1 [Piece 2, 5–8 cm]). Subhedral to euhedral olivine microphenocrysts make up to 2% of the rock and are <1 mm in size. The groundmass is composed of acicular plagioclase laths, quench clinopyroxene, and minor amounts of fresh brown glass and skeletal opaque minerals. Small melt inclusions are hosted in olivine microphenocrysts (Fig. F3).
Basalts from Sections 209-1273A-1R-1 and 209-1273B-1R-1 and 3R-1 show no visible alteration, except thin coatings of Fe-Mn oxides. A pillow-rind breccia in Section 209-1273B-2R-1 (Piece 1) is ~10% altered to clay and Fe oxyhydroxide, mostly within the red clayey breccia cement. Piece 2 of that section contains small rubbly pieces of the same pillow-rind breccia along with fresh basalt. Similar to all other pieces from Section 209-1273C-1R-1, Pieces 12 and 13 are fresh basalt, except acicular zeolite and green clay lining vesicle walls.
The harzburgite recovered from Hole 1273C (Sample 209-1273C-1R-1, 46–48 cm) has a protogranular texture and the only fresh mineral is spinel (Fig. F4). The harzburgite is completely altered, with olivine replaced by serpentine and brown clay, whereas orthopyroxene is altered to talc, serpentine, and minor chlorite and tremolite.