THIN SECTION:	"U1301B-15R-4, 66-68 cm (Piece 6)"				TS #	28	Unit:4C	"OBSERVER: MS, RC"
ROCK NAME: 	Moderately olivine-clinopyroxene-plagioclase phyric basalt							
WHERE SAMPLED:	Flow interior (alteration halo)							
GRAIN SIZE:	Microcrystalline							
TEXTURE:	"Intersertal to intergranular, glomeroporphyritic, vesicular"							
PRIMARY	PERCENT 	PERCENT	SIZE (mm)			APPROX.		
MINERALOGY	PRESENT 	ORIGINAL	min.	max.	av.	COMP.	MORPHOLOGY	COMMENTS
PHENOCRYSTS								
Plagioclase	3	3	1	1.5	1.2		Euhedral to subhedral	"Some crystals have a honeycomb texture, some contain glass inclusions."
Clinopyroxene	3	3	0.4	1	0.7		Euhedral to anhedral	"Present singly, in glomeroporphyritic clots associated with plagioclase lath."
Olivine	0	1	0.2	1.8	1		Euhedral to subhedral	Completely replaced by saponite.

GROUNDMASS								
Plagioclase	37	37		<1			Euhedral	Microlaths.
Clinopyroxene	20	20		<0.4			Euhedral to anhedral	
Olivine	0	Tr		<0.2			Subhedral	
Mesostasis	26	47						

SECONDARY			SIZE (mm)					
MINERALOGY	PERCENT		min.	max.	av.		REPLACING / FILLING	COMMENTS
Saponite	4						"Olivine, mesostasis, vein"	Fibrous to granular brown-green saponite.
Feox + iddingsite	7						"Olivine, vesicles, vein"	


VESICLES/			SIZE (mm)					
CAVITIES	PERCENT	 LOCATION	min.	max.	av.		FILLING / MORPHOLOGY	COMMENTS

COMMENTS : 	"The alteration halo is zoned: 8 mm brown (dominantly Feox), 3 mm green (dominantly saponite). Vein (0.2 mm) cuts across halo."