U.S. Geological Survey Certificate of Analysis

Dunite, Twin Sisters Mountain DTS-2B

Material used in the preparation of this reference material was collected from a quarry located in Twin Sisters Range, approximately 20-due-miles east of Bellingham, Washington. The Twin Sisters dunite is composed of virtually unaltered, coarse grained enstatite bearing dunite with accessory amounts of chromite and chromium diopside (Ragan, D.M., 1963). Mineralogical analysis of DTS-2B reveals that the dominant mineral is Fosterite (90+%) with minor amounts of chromite and trace amounts of lizardite. DTS-2B was collected from the same general location as DTS-1.

Element concentrations were determined in a round robin study involving 20 international laboratories. Recommended values are listed when analytical results provided by three independent laboratories using a minimum of two independent analytical procedures are in statistical agreement. Information values with standard deviations are listed when at least two independent laboratories have provided information. Information values without standard deviations represent information from a single laboratory or analytical procedure.

Recommended Values | Certificate Information | Bibliography | Glossary | Notes | Order and Pricing Information

Element Wt % ± Oxide Wt % ±
Al 0.24 0.03 Al2O3 0.45 0.06
Ca 0.09 0.01 CaO 0.12 0.01
Fetot 5.43 0.15 Fe2O3tot 7.76 0.21
Mg 29.8 1.1 MgO 49.4 1.8
Si 18.4 0.4 SiO2 39.4 0.8
Element µg/g ± Element µg/g ±
Co 120 10 Ni 3780 220
Cr 15500 1100 V 22 8
Mn 830 40 Zn 45 5
Element Wt % ± Element µg/g
Fe(II) 4.27 0.20 Ba 16
Na 0.02 Cu 3
Ge 0.7
Pb 4
Rb 2
Sb 0.6
Sc 3

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Certificate Information

Denver, Colorado
March 2001

Dr. Stephen Wilson
U.S. Geological Survey
Crustal Imaging and Characterization Team

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Ragan, D.M., 1963, Emplacement of the Twin Sisters Dunite, Washington: American Journal of Science, 261:549-565.

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Symbol Definition
± One standard deviation
Wt % Weight percent of element/oxide as received
µg/g Micrograms of element per gram of sample, as received

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Unless otherwise indicated, total element concentrations are reported for material on an as-received basis.

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Order and Pricing Information

Placing an Order

USGS reference materials may be obtained directly from Dr. Stephen A. Wilson. The price for each reference material is listed in U.S. dollars and are subject to change. For domestic orders, this cost includes all shipping and handling charges using normal mail delivery by the U.S. Postal Service. For foreign orders, delivery charges will be added to the final bill. Urgent requests for reference materials should be initiated by Fax or e-mail. If required, expedited delivery is available with any additional shipping charges added to the final bill.

To order a USGS Reference Material, please contact Dr. Stephen Wilson or use the downloadable form: Order Form (Word) (22 KB) or Order Form (PDF) (238 KB).

Dr. Stephen A. Wilson
U.S. Geological Survey
Box 25046, MS 964D
Denver, CO 80225
Tel: 303-236-2454
FAX: 303-236-3200 or 303-236-1425
Email: (swilson@usgs.gov)

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Payments for domestic or international orders using a credit card receive a 10% discount on the per bottle price.

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Please download the agreement form and follow the instructions on the form when placing your order.

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