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Oxide and Cation Compositions of Feldspar Grains from Drill Core of the Duluth Complex, Minnesota


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Schulte, R.F., Seal, R.R., Piatak, N.M., and Woodruff, L.G., 2017, Oxide and cation compositions of feldspar grains from drill core of the Duluth Complex, Minnesota: U.S. Geological Survey data release,


The table contains oxide and cation compositions of feldspar grains from drill core of the Duluth Complex. The oxides were determined by electron probe microanalysis (EPMA) and are are reported in weight percent (wt%). The cations were then calculated and are reported in mole percent (mol%). Feldspar grains are a group of rock-forming tectosilicate minerals with potassium (K), sodium (Na), and calcium (Ca) endmembers. Anorthite has a chemical formula CaAlSi3O8; albite has the formula NaAlSi3O8; and orthoclase has the chemical formula KAlSi3O8. To better understand the composition of the measured feldspars, we calculated the anorthite content (An%) as (Ca/(Ca+Na+K)) x 100 and report the values in mol%. Albite (Ab%) was calculated as [...]


Point of Contact :
Nadine Piatak
Originator :
Ruth F. Schulte, Robert R. Seal, II, Nadine M. Piatak, Laurel G. Woodruff
Metadata Contact :
Peter N Schweitzer
Publisher :
U.S. Geological Survey
Distributor :
GS ScienceBase
USGS Mission Area :
Energy and Minerals
SDC Data Owner :
Mineral Resources Program

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Feldspar Compositions.csv
“Feldspar Compositions”
54.44 KB


Data were collected in order to determine the chemical composition of feldspar grains found in drill core from the Duluth Complex. This data enabled us to calculate the anorthite content (An%) of the feldspars, which were then used to determine the neutralizing potential (NP) of the feldspar grains. This data was added to the NP of other silicate minerals in the Duluth Complex drill cores to give a total NP of the silicate minerals, which may impact the acid-generating potential of waste rock from proposed Cu-Ni-PGM mining.

Additional Information


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DOI doi:10.5066/F7FJ2F9B

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