U.S. Geological Survey Geochemical Reference Materials and Certificates
U.S. Geological Survey
Certificate of Analysis
The rhyolite, from Glass Mountain, Siskiyou County, California, was collected from a single block of massive obsidian near the terminal front of a Holocene obsidian flow. The sample is classified as a rhyolite on the basis of its high silica and total alkali contents, and it is assigned to the calc-alkali series because of its high CaO to total iron ratio.
The concentrations were determined by cooperating laboratories using a variety of analytical methods. Values reported are derived from international data compliations (Abbey, 1983, Gladney and Roelandts, 1988, Govindaraju, 1994). Initial USGS reports (Flanagan, 1976) provide background information on this material.
Recommended Values | Certificate Information | Bibliography | Glossary | Notes
| Oxide | Wt % | ± | Oxide | Wt % | ± | |
|---|---|---|---|---|---|---|
| SiO2 | 73.4 | 0.53 | MnO | 0.036 | 0.004 | |
| Al2O3 | 13.7 | 0.19 | Na2O | 4.07 | 0.15 | |
| Fe2O3 | 0.50 | 0.01 | K2O | 4.30 | 0.10 | |
| FeO | 1.27 | 0.05 | TiO2 | 0.27 | 0.02 | |
| Fe2O3 T | 1.86 | 0.03 | CaO | 1.15 | 0.07 | |
| MgO | 0.28 | 0.03 | ||||
| Element | µg/g | ± | Element | µg/g | ± | Element | µg/g | ± | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Ag | 0.11 | 0.008 | Eu | 0.66 | 0.08 | Sb | 1.3 | 0.1 | ||
| As | 3.0 | 0.4 | F | 340 | 30 | Sc | 4.4 | 0.3 | ||
| B | 28 | 3 | Ga | 15 | 2 | Sm | 4.3 | 0.3 | ||
| Ba | 810 | 46 | Gd | 3.7 | 0.4 | Sn | 4.1 | 0.4 | ||
| Be | 2.4 | 0.2 | La | 24 | 1.1 | Sr | 110 | 10 | ||
| Br | 1.3 | 0.1 | Li | 57 | 8 | Ta | 0.95 | 0.1 | ||
| Ce | 47 | 4 | Lu | 0.4 | 0.03 | Th | 15 | 1.3 | ||
| Cl | 510 | 50 | Mn | 280 | 30 | U | 5.8 | 0.5 | ||
| Co | 2.0 | 0.2 | Mo | 2.3 | 0.5 | V | 13 | 2 | ||
| Cs | 9.6 | 0.6 | Nb | 8.9 | 0.6 | W | 1.5 | 0.18 | ||
| Cu | 12 | 1.4 | Nd | 19 | 1 | Yb | 2.6 | 0.3 | ||
| Dy | 4.1 | 0.1 | Pb | 24 | 3 | Zr | 220 | 20 | ||
| Rb | 150 | 8 | ||||||||
| Element | µg/g | Element | µg/g | Element | µg/g | ||
|---|---|---|---|---|---|---|---|
| Cr | 3.7 | Y | 25 | Zn | 32 |
Denver, Colorado
revised March 1995
David B. Smith
Central Region Mineral Resources Team (formerly Branch of Geochemistry)
Abbey, S., 1983, Studies in "Standard Samples" of Silicate Rocks and Minerals 1969-1982, Canadian Geological Survey Paper 83-15, p-114.
Flanagan, F.J., 1976, Descriptions and Analyses of Eight New USGS Rock Standards, U.S. Geological Survey Professional Paper 840, p 192.
Gladney, E.S., and Roelandts, I., 1988, 1987 Compilation of Elemental Concentration Data for USGS BHVO-1, MAG-1, QLO-1, RGM-1, SCo-1, SDC-1, SGR-1, and STM-1, Geostandards Newsletter, 12: 253-362.
Govindaraju, K., 1994, 1994 Compilation of Working Values and Descriptions for 383 Geostandards, Geostandards Newsletter, 18:1-158.
| Symbol | Definition |
|---|---|
| Fe2O3T | Total iron expressed as Fe2O3 |
| Ctot | Total carbon concentration |
| Stot | Total sulfur concentration |
| Wt % | Percent of total element concentration |
| µg/g | Total element concentration expressed as micrograms of element per gram of solid sample |
| ± | One standard deviation |
Unless otherwise indicated total element concentrations are reported for material on an as-received basis, i.e., no drying.
This geochemical reference standard is no longer available.
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