"168-1029A-25X-03 (piece 12, 83-87 cm)" ROCK NAME: Glomeroporphyritic plagioclase-olivine basalt GRAIN SIZE: Microcrystalline to cryptocrystalline TEXTURE: Plumose; sheaf-spherulitic +/- honeycomb; glomeroporphyritic; vesicular PRIMARY MINERALOGY PERCENT PRESENT PERCENT ORIGINAL SIZE (mm) COMPOSITION MORPHOLOGY COMMENTS PHENOCRYSTS Olivine 0 0.2 0.5-0.6 (Ave 0.6) Subhedral to euhedral Occur singly or associated with plagioclase laths. Completely replaced by clay minerals (granular saponite and celadonite). Highly fractured. Plagioclase 2.4 2.4 0.5-1.0 (Ave 0.8) Euhedral; skeletal Form elongate laths and stubby crystals. Occur singly and within glomeroporphyritic clots with pyroxene microcrysts. GROUNDMASS Plagioclase 6.6 6.6 0.05-0.4 (Ave 0.1) Euhedral to anhedral Form large glomeroporphyritic clusters (up to 6mm) associated with pyroxene; also occurs singly. Some swallowtail and hollow crystals. Olivine 0 0.2 0.2-0.4 (Ave 0.3) Anhedral to skeletal "Completely replaced by clay minerals, often consisting of intergrowths of saponite +/- iddingsite +/- celadonite. Occur singly, associated with plag laths, or at the edges of plag-px glomeroporphyritic clots." Clinopyroxene 4.6 4.6 0.05-0.4 (Ave 0.1) Anhedral to subhedral Form large glomeroporphyritic clusters (up to 6mm) associated with plagioclase; sparse amount of small (<=0.1mm) grains occur singly. Pyrite Tr Tr <=0.03 (Ave 0.01) Granular to globular Disseminated through the mesostasis. Some round globules (0.02mm) occur -- immiscible droplets. Mesostasis 84.6 85.4 SECONDARY MINERALOGY PERCENT REPLACING/ FILLING COMMENTS: Saponite 1 Vesicles; olivine; vein; mesostasis Pale brown; cryptocrystalline granular to fibrous. Celadonite 0.2 Vesicles; olivine; vein; mesostasis Massive to microcrystalline to fibrous; bright green. Iddingsite Tr Vesicle; olivine; vein Massive texture; red. Pyrite/pyrrhotite Tr Vesicle; mesostasis Completely fills one 0.15mm vesicle; disseminated in groundmass. VESICLES/ CAVITIES PERCENT LOCATION SIZE (mm) FILLING SHAPE COMMENTS: Gas vesicles 0.6 Even 0.1-0.3 (Ave 0.2) Clay Round to ovoid "Filling varies in different zones from celadonite + iddingsite to saponite, to saponite + celadonite. When all phases are together, celadonite is the first phase to form, whereas saponite is the last." Cavities Tr Near rim <=0.6 Clay Irregular "As vesicles; commonly have granular celadonite rim, followed by granular to fibrous saponite +/- celadonite fill. Some have an iddingsite rim and mixed iddingsite + saponite + celadonite fill." COMMENTS: Parallel bands of different textures occur in the mesostasis. Parallel to these are pyrite/pyrrhotite rich zones consisting of 0.02-0.03mm granules. These interstitial sulfides are preferentially localized along the edge of the oxidation halo. "168-1029A-25X-04 (piece 3, 18-21 cm)" ROCK NAME: GRAIN SIZE: Microcrystalline to cryptocrystalline TEXTURE: sheaf-spherulitic; glomeroporphyritic; vesicular PRIMARY MINERALOGY PERCENT PRESENT PERCENT ORIGINAL SIZE (mm) COMPOSITION MORPHOLOGY COMMENTS PHENOCRYSTS Olivine 0 0.6 0.4-0.6 Euhedral Completely replaced by clays (celadonite + saponite); occur singly and associated with plagioclase laths. Plagioclase 1.6 1.6 0.6-1.6 (Ave 0.8) Euhedral to subhedral "Laths and stubby crystals. One lath is 3.6mm long, with simple zoning and a core rich in glass inclusions (along lamellae). Simple and oscillatory zoning; sector zoning in stubby crystals. Occur singly or in glomeroporphyritic clots." Pyroxene Tr Tr 0.4-0.8 Subhedral "Occur singly, but more frequently in glomeroporphyritic clots or associated with plagioclase laths." GROUNDMASS Plagioclase 6.4 6.4 0.05-0.5 Euhedral to skeletal "Microlaths, microlites and quench crystals (swallowtails and hollow). Occur singly and in glomeroporphyritic clots." Olivine 0 0.2 0.1-0.3 (Ave 0.2) Subhedral to euhedral Completely replaced by granular saponite and/or fibrous celadonite. Clinopyroxene 5 5 0.05-0.35 (Ave 0.2) Subhedral to granular "Some single grains (0.05-0.1mm), but most are in glomeroporphyritic clots or attached to plagioclase laths." Pyrite Tr Tr 0.005-0.05 Anhedral to granular Disseminated throughout the groundmass. Some pyrite grains are <=0.05mm; most are <=0.01mm. Mesostasis 83.8 84 SECONDARY MINERALOGY PERCENT REPLACING/ FILLING COMMENTS: Saponite 0.8 Olivine; vesicles; mesostasis Tan brown; granular. Occurs as pure saponite or mixed with celadonite. Celadonite 0.2 Olivine; vesicles; mesostasis "Bright green, fibrous. Mixed with saponite; restricted in the most part to the alteration halo." Iddingsite Tr Vesicles Fills or lines some vesicles in the alteration halo. Hematite Tr Vesicles Fills or lines some vesicles in the alteration halo. Pyrite/pyrrhotite Tr Vesicles <=0.03mm globules and granules in vesicle linings at the rim. VESICLES/ CAVITIES PERCENT LOCATION SIZE (mm) FILLING SHAPE COMMENTS: Gas vesicles 2.2 Even 0.1-0.6 (Ave 0.4) "Empty or clay, hematite" Round to ovoid "In the interior of the rock, the vesicles are empty. In the alteration halo they are lined to filled by celadonite; saponite + celadonite mixture; +/- saponite; +/- iddingsite; +/- hematite from rim to core. " Cavities Tr Even <=0.5 "Empty or clay, hematite" Irregular As above. COMMENTS: "Vesicles can be filled by a series of layers, or have a more intricate mixed central fill."