SPI Supplies Individual Loose Microanalysis Standard Item, Minerals Group, Obsidian (alternate to AS

SPI Supplies Individual Loose Microanalysis Standard Item, Minerals Group, Obsidian (alternate to AS
SPI Supplies Individual Loose Microanalysis Standard Item, Minerals Group, Obsidian (alternate to AS
$207.48
AvailabilityContact for Availability
ItemAS1255-AB

This is a reflected light micrograph of a polished, carbon coated obsidian grain. The identifying etched label, which is a feature of our standards, is invaluable for navigating in an electron beam instrument. Obsidian is a volcanic glass containing the full range of rock-forming elements from hydrogen to iron. Because of its glassy state, the alkali elements Na and K are not tightly bound and may therefore migrate, giving instability in intense electron bombardment. However, the composition has been well established through repeated analysis by classes of students, it is a most useful standard for general use in silicate analysis.

Element Wt % Oxide Wt %
H 0.09 H2O 0.80
O 48.63
F 0.07 F 0.07
Na 3.01 Na2O 4.06
Mg 0.04 MgO 0.07
Al 6.94 Al2O3 13.11
Si 34.56 SiO2 73.94
Cl 0.36 Cl 0.36
K 4.18 K2O 5.04
Ca 0.54 CaO 0.76
Ti 0.06 TiO2 0.10
Mn 0.05 MnO 0.06
Fe 1.34 FeO 1.72


Sum 99.9 Sum 100.1