Table T7. Classification of sulfide samples and other hydrothermal precipitates recovered during Leg 193.

Type and textural description	Sulfide minerals	Gangue minerals	Major features/comments
1. Disseminated sulfide: widely dispersed disseminations of pyrite in altered volcanic rock.	Trace to minor fine to fine-grained pyrite, typically subhedral to euhedral. Extremely fine grained pyrite, confirmed by X-ray diffraction, turns its host anhydrite-silica-clay black. Fine-grained black (Fe rich) sphalerite and chalcopyrite in some samples.	Major to minor anhydrite, silica, and clay minerals.	Part of the intense pervasive alteration. Commonly also contains a fine network of thin (<0.5 mm) veinlets. Sphalerite is paragenetically later than pyrite.
2. Anhydrite ± quartz-pyrite vein: coarse to fine clear anhydrite crystals with or without quartz (or undifferentiated silica) and clay.	Trace to minor euhedral fine-grained pyrite.	Major coarse tabular anhydrite. Minor to major granular or euhedral quartz. Trace to minor fine-grained octahedral magnetite.	Fluid inclusions in the anhydrite. Pyrite forms a druse on the anhydrite. Paragenesis is anhydrite or quartz followed by pyrite.
2a. Vesicle linings of anhydrite quartz-pyrite: some have been accessed by an anhydrite ± quartz-pyrite veinlet.			Walls of some vesicles are silicified. Amount of sulfide depends on number of vesicles. Most, but not all, samples have <5% sulfide.
3. Anhydrite-magnetite ± pyrite veins: magnetite and pyrite as disseminations and in anhydrite veinlets with distinct alteration halos cutting a matrix of anhydrite, silica, and clay minerals. Some aggregates of magnetite have a spherical shape.	Trace to minor very fine grained magnetite and pyrite. Interstitial chalcopyrite and trace yellow sphalerite.	Major to minor very fine grained anhydrite, quartz, and clay.	Magnetite is in small vugs in anhydrite. Magnetite can have a spherical to framboidal shape.

Note: By convention, samples contain 5% sulfide.