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dc.contributor.authorYang, H.
dc.contributor.authorGu, X.
dc.contributor.authorGibbs, R.B.
dc.contributor.authorDowns, R.T.
dc.date.accessioned2022-11-23T18:21:18Z
dc.date.available2022-11-23T18:21:18Z
dc.date.issued2022
dc.identifier.citationYang, H., Gu, X., Gibbs, R. B., & Downs, R. T. (2022). Loomisite, Ba[Be2P2O8]•H2O, the first natural example with the zeolite ABW-type framework, from Keystone, Pennington County, South Dakota, USA. Mineralogical Magazine.
dc.identifier.issn0026-461X
dc.identifier.doi10.1180/mgm.2022.117
dc.identifier.urihttp://hdl.handle.net/10150/666905
dc.description.abstractA new beryllophosphate mineral species, loomisite (IMA 2022-003), ideally Ba[Be2P2O8]•H2O, was found from the Big Chief mine near Keystone, Pennington County, South Dakota, USA. It occurs as divergent sprays of very thin bladed crystals with a tapered termination. Individual crystals are found up to 0.80 x 0.06 x 0.03 mm. Associated minerals include dondoellite, earlshannonite, mitridatite, rockbridgeite, jahnsite-(CaMnFe), and quartz. No twinning or parting is observed macroscopically. Loomisite is murky white in transmitted light, transparent with white streak and silky to vitreous luster. It is brittle and has a Mohs hardness of 3½-4, with perfect cleavage on (100) and (-110). The measured and calculated densities are 3.46(5) and 3.512 g/cm3, respectively. Optically, loomisite is biaxial (+), with α = 1.579(5), β = 1.591(5), γ = 1.606(5) (white light), 2V (meas.) = 82(2)º, 2V (calc.) = 85º. It is non-pleochroic under polarized light, with a very weak (r > v) dispersion. The mineral is insoluble in water or hydrochloric acid. An electron microprobe analysis, along with the BeO content measured with an ICP-MS, yields an empirical formula (based on 9 O apfu) (Ba0.96Ca0.06)Ʃ1.02[(Be1.96Fe0.06)Ʃ2.02P1.99O8]•H2O, which can be simplified to (Ba,Ca)[(Be,Fe)2P2O8]•H2O. Loomisite is monoclinic, with space group Pn and unit-cell parameters a = 7.6292(18), b = 9.429(2), c = 4.7621(11) Å, β = 91.272(5)◦, V= 342.47(14) Å3, and Z = 2. Its crystal structure is characterized by a framework of corner-sharing PO4 and BeO4 tetrahedra. The framework can be considered as built from the stacking of sheets consisting of 4- and 8-membered rings (4.82 nets) along [001] or hexagonal layers (63 nets) along [010]. The extra-framework Ba2+ and H2O are situated in the channels formed by the 8-membered rings. Topologically, loomisite represents the first natural example with the zeolite ABW-type framework, which is adopted by over 100 synthetic compounds with different chemical compositions. © 2022 Cambridge University Press. All rights reserved.
dc.language.isoen
dc.publisherCambridge University Press
dc.rightsCopyright © The Author(s), 2022. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland.
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectABW-type framework
dc.subjectberyllophosphate
dc.subjectcrystal structure
dc.subjectLoomisite
dc.subjectnew mineral
dc.subjectX-ray diffraction
dc.subjectzeolite
dc.titleLoomisite, Ba[Be2P2O8]•H2O, the first natural example with the zeolite ABW-type framework, from Keystone, Pennington County, South Dakota, USA
dc.typeArticle
dc.typetext
dc.contributor.departmentDepartment of Geosciences, University of Arizona
dc.identifier.journalMineralogical Magazine
dc.description.note12 month embargo; published online: 20 October 2022
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.
dc.eprint.versionFinal published version
dc.source.journaltitleMineralogical Magazine


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