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GEOREF RECORD

Mineralogical studies of the nitrate deposits of Chile; VI, Hectorfloresite, Na (sub 9) (IO (sub 3) )(SO (sub 4) ) (sub 4) , a new saline mineral

George E. Ericksen, Howard T. Evans, Mary E. Mrose, James J. McGee, John W. Marinenko and Judith A. Konnert
Mineralogical studies of the nitrate deposits of Chile; VI, Hectorfloresite, Na (sub 9) (IO (sub 3) )(SO (sub 4) ) (sub 4) , a new saline mineral
American Mineralogist (October 1989) 74 (9-10): 1207-1214

Abstract

The new mineral hectorfloresite, known to occur in only one locality in the nitrate fields of northern Chile, consists of tiny prismatic crystals, generally less than 1 mm long and 0.2 mm in diameter, in cavities in dense nitrate ore consisting of saline-cemented silt, sand, and small rock fragments. The cavities also contain euhedral crystals of halite, darapskite, and glauberite. Hectorfloresite is named for Hector Flores W. (1906-1984), a pioneer Chilean geologist. Hectorfloresite is monoclinic and occurs as pseudohexagonal prismatic crystals consisting of multiple prismatic twins. The space group is P21/a, with a = 18.775(4) Aa, b = 6.9356(7) Aa, c = 14.239(2) Aa, beta = 108.91(2) degrees , and Z = 4[Na9(IO3)(SO4)4]. X-ray powder patterns of natural hectorfloresite show the following strong lines (dmeas, I/I0, hkl): 3.880(100)(411), 2.700(80)(604), 2.788(30)(222), 1.9420(20)(822), 4.69(15)(401), 6.17(10)(011), 1.6800(10)(632), 1.5607(10)(606), and 1.5533(10)(609). Crystal forms are a{100}, c{001), and q{212}. The new mineral has a hardness of about 2, lacks cleavage, and shows a conchoidal fracture. The measured specific gravity of synthetic hectorfloresite is 2.80(3) and the calculated density is 2.90 g/cm3. Hectorfloresite is biaxial negative with a = 1.493(2), beta = 1.521(2), and gamma = 1.523(2); 2VX = 26(2) degrees . The new mineral is one of two double salts in the system NaIO3-Na2SO4-H2O. Microprobe analyses of crystals of natural hectorfloresite show the average composition to be 34.5% Na2O, 23.2% I2O5, and 42.3% SO3. Chemical analyses of synthetic hectorfloresite show essentially the same composition. The formula based on these analyses is Na9(IO3)(SO4)4. This composition was confirmed by crystal-structure analysis of natural hectorfloresite.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 74
Serial Issue: 9-10
Title: Mineralogical studies of the nitrate deposits of Chile; VI, Hectorfloresite, Na (sub 9) (IO (sub 3) )(SO (sub 4) ) (sub 4) , a new saline mineral
Affiliation: U. S. Geol. Surv., Reston, VA, United States
Pages: 1207-1214
Published: 198910
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 8
Accession Number: 1990-013355
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
S21°30'00" - S17°34'60", W70°30'00" - W68°19'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 1990
Program Name: USGSOPNon-USGS publications with USGS authors
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