1989/12/01 by J. Pašava, Jan Pašava, F. Pertlik +2
Materials Science · #Crystal Structures and Properties #Glass properties and applications #Solid-state spectroscopy and crystallography
paper · doi:10.1180/minmag.1989.053.373.03
crossref issued 1989/12/01 · crossref published 1989/12/01 · crossref published-print 1989/12/01 · openalex publication_date 1989/12/01 · crossref created 2006/12/07 · crossref published-online 2018/07/05 · crossref deposited 2021/02/04 · openalex created_date 2025/10/10 · crossref indexed 2026/07/30 · openalex updated_date 2026/07/31
Abstract The new mineral bernardite has been identified on one specimen from Allchar, Macedonia, Yugoslavia, together with orpiment and realgar. It forms black crystals, the size of which may exceed 1 mm. The streak is deep red; on an arbitrarily oriented section R (589nm) ranges from 23.8 to 24.7% in air, from 10.2 to 11.6% in oil. Microprobe analyses together with an X-ray structure analysis suggest the ideal formula TlAs 5 S 8 , with a possible replacement of As by Sb up to 15 wt. %. Monoclinic; a 15.647(4), b 8.038(3), c 10.750(3) Å, β 91.27(3)°; space group P 2 1 / c ; Z = 4; R = 0.049, w R = 0.036 for 2410 reflections. The atomic arrangement consists of a 3-dimensional As 5 S 8 framework with eight-coordinated T1 in its holes. The mineral is named for Doc. Dr Jan H. Bernard, Prague, Czechoslovakia.