Fluorapophyllite-(NH4), NH4Ca4(Si8O20)F center dot 8H(2)O, a new member of the apophyllite group from the Vechec quarry, eastern Slovakia
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F20%3A00117569" target="_blank" >RIV/00216224:14310/20:00117569 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1180/mgm.2020.44" target="_blank" >https://doi.org/10.1180/mgm.2020.44</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1180/mgm.2020.44" target="_blank" >10.1180/mgm.2020.44</a>
Alternative languages
Result language
angličtina
Original language name
Fluorapophyllite-(NH4), NH4Ca4(Si8O20)F center dot 8H(2)O, a new member of the apophyllite group from the Vechec quarry, eastern Slovakia
Original language description
The new mineral fluorapophyllite-(NH4), ideally NH4Ca4(Si8O20)F center dot 8H(2)O, was found at the Vechec andesite quarry located near Vechec village, Vranov nad Topl'ou Co., Pregov Region, Slovak Republic. It occurs in cavities of quartz-illite-saponite-tobelite xenolith embedded in pyroxene andesite. Fluorapophyllite-(NH4) is associated with calcite, tridymite, pyrite, chabazite-Ca and heulandite-Ca. It forms clusters, aggregates or crystalline crusts consisting of individual, well-developed crystals up to 4 mm in size, exhibiting the forms {110}, {101} and {001}. The mineral is colourless to light pink and translucent with white streak and vitreous to pearly lustre; it is nonfluorescent under ultraviolet radiation. The Mohs hardness is similar to 4% to 5, tenacity is brittle, fracture is irregular, and there is perfect cleavage on {001}. The calculated density is 2.325 g cm(-3). Fluorapophyllite-(NH4) is optically uniaxial (+) with omega = 1.5414(5) and epsilon = 1.5393(8) (lambda = 589 nm). It is non-pleochroic. The empirical formula (based on 29 O + F apfu) is [(NH4)(0.55)K0.32Na0.07Ca0.06](Sigma 1.00)(Ca4.01Mg0.02)(Sigma 4.03) Si7.97O20[F-0.84(OH)(0.16)](Sigma 1.00)center dot 8H(2)O. Fluorapophyllite-(NH4) is tetragonal, space group P4/mnc, a = 8.99336(9) angstrom, c = 15.7910(3) angstrom, V= 1277.18(3) angstrom(3) and Z = 2. The seven strongest X-ray powder diffraction lines are [d(obs) in angstrom,(I,%)(hkl)1: 7.897(32)(002), 7.812(13) (101), 4.547(14)(103), 3.946(100)(004), 2.985(39)(105), 2.4841(11)(215) and 1.5788(12)(00.10). The crystal structure of fluorapophyllite-(NH4), refined to R-1 = 0.0299 for 743 unique (I > 3 sigma I) observed reflections, confirmed that the atomic arrangement is very similar to that of the other members of the apophyllite group. The new mineral is named according to the current nomenclature scheme for apophyllite-group minerals and is an NH4 dominant analogue of fluorapophyllite-(K), fluorapophyllite-(Na) and fluorapophyllite-(Cs).
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10504 - Mineralogy
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Mineralogical Magazine
ISSN
0026-461X
e-ISSN
1471-8022
Volume of the periodical
84
Issue of the periodical within the volume
4
Country of publishing house
GB - UNITED KINGDOM
Number of pages
7
Pages from-to
533-539
UT code for WoS article
000566874000005
EID of the result in the Scopus database
2-s2.0-85091454778