Name: Rhyolitic obsidian
Type: rock
Class: Igneous
Subclass: Intermediate
Particle Size: Fine
Sample No.: Obsidian_H1
Owner: JHU
Wavelength Range: All
Origin: Mono Lake, California  via Smithsonian (Cat. No.111123-60)
Collection Date: N/A
Description: The sample from which the powder was derived is a black homogenous glass with good conchoidal fracture.Particle size was 0-75 micrometers. Original ASTER Spectral Library name was jhu.becknic.rock.igneous.intermediate.fine.obsidi1.spectrum.txt
Composition:

Petrographic Description:  The sample is chiefly a structurless glass which is
isotropic and colorless in this section.  There are fluidal arrangements of gas 
inclusions and microlites of biotite, augite, probably feldspars and other
unidentified phases.  High magnification shows trichites.  This appearance is 
not constant throughout the mass.

Microprobe Analysis:  None.

Chemical Analysis:
SiO2  75.78
CaO  0.81
Al2O3  12.39
Na2O  4.00
Fe2O3  0.22
K2O  4.64
FeO  1.25
MgO  0.31
TOTAL  99.4
