Volcanic ash, Mount St. Helens

Practical significance

Interpretation of remote sensing data. Analogues of other planets' atmospheric dust, and dust in comets, asteroids, and circumstellar shells.

Origin

Mount St. Helens volcano in southwest Washington, USA. The particles were collected 6 km north of the crater after a large eruption on 18 May 1980. The coarse fraction was removed by sieving.

Main constituent
64 wt% glass, plagioclase feldspar, opx, amphibole, magnetite, ilmenite, cpx
Color
Light gray
Particle size Fraunhofer: reff (μm)
4.1
Particle size Fraunhofer: veff
9.5
Size distribution plot:
Size Distribution Mount St. Helens
Size distribution table
size_sthelens.txt
SEM/TEM images:
Mount St. Helens SEM Image 1
Mount St. Helens SEM Image 2
All SEM/TEM images (zip file)
sem_sthelens_0.zip
Scattering matrix (1) wavelength in nm
632.80 nm
Scattering matrix (1) table
matrix_sthelens_633nm.txt
Scattering matrix (1) plot:
Scattering matrix elements Mount St. Helens
Refractive index

Estimated to be in the range [1.48-1.56] + i0.0018.

Angle range (deg)
[3,173]
Reference/s
Muñoz et al., 2004