Name: Augite-hypersthene Andesite	
Type: rock	
Class: Igneous	
Subclass: Intermediate	
Particle Size: Fine	
Sample No.: Andesite_H1	
Owner: JHU	
Wavelength Range: All	
Origin: Saipan, via Smithsonian (Cat. Number. NMNH 108982-135)
Collection Date: N/A
Description: Sample from which the powder is derived is brown on the weathered surface and dk. gray on fresh surfaces; porphyritic, with approx. < 1mm phenocrysts (plagioclase laths, pyroxene and opaques, in that order of abundance) making up about 25-30% of the rock. Groundmass gray.Particle size was 0-75 micrometers. Original ASTER Spectral Library name was jhu.becknic.rock.igneous.intermediate.fine.andesi1.spectrum.txt
Composition:

Petrographic Description:  The modes for phenocrysts for this sample gave
26.75% plagioclase, 8.5% augite, 1.05% magnetite, 0.95% hypersthene, and
62.75% groundmass.  The groundmass for these samples consists of 
labradorite, augite, hypersthene, magnetite, ilmenite, trydimite as 
isolated grains and aggregates of small wedge-shaped crystals closely associated
with small patches of intergrown granular quartz and chalcedony, anorthoclase, 
and  partly devitrified glass.

Microprobe Analysis:  The composition of the plagioclase phenocrysts was 
found to range from An59 to An62 (labradorite), while the composition in the 
groundmass ranged from An50 to An55.  The augite phenocryst composition 
was Wo 34%, En 43%, Fs 23%, that of the hypersthene phenocrysts was En 67%, Fs 33%.  
Augite in the groundmass was W0 24%, En 45%, Fs 31%.

Chemical Analysis:
SiO2  57.20
CaO  8.85
TiO2  0.54
Na2O  2.50
Al2O3  16.35
K2O  0.68
Fe2O3  2.23
H2O  0.90
FeO  5.93
P2O5  0.36
MnO  0.14
MgO  4.65
TOTAL  100.3
