Primary standard
NOTES: Widely used electron probe standard. Homogeneous, but stay away from cracks and chalcopyrite grains (bright in BSE, red in X-ray map). In the upper right corner of the grain (see lower-left BSE image) there are some apparent inhomogeneities. EDS analyses show no compositional difference, so the differences in BSE brightness may be caused by crystallographic orientation, such as twinning. To be on the safe side, stick with the BSE-brighter areas.
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 | Empty |
| Position | 26 |
| Mineral | Albite, Amilia |
| Sample Name | Amilia |
| Type | Feldspar |
| Nominal formula | NaAlSi3O8 |
| Supplier | Cannon Microprobe, Seattle, WA |
| Source | Amelia County, Virginia. Harvard oxygen standard |
| Original reported analysis | Amilia albite, Harvard oxygen standard |
| Composition quality | Primary standard |
| Comments | Analysis modified slightly to better fit stoichiometric constraints. |
| O Na Al Si K Ca Fe | 48.72 8.52 10.36 31.95 0.22 0.17 0.06 |
