6533b7d1fe1ef96bd125cddc

RESEARCH PRODUCT

Crystal structure of SrMn2(Si2O7)(OH)2 H2O, a new mineral of the lawsonite type

Thomas ArmbrusterVladimir BermanecRoland Oberhänsli

subject

CrystalCrystallographyMaterials scienceRuiziteMineralOctahedronLawsoniteGeochemistry and Petrologylawsonite; soro-silicate; crystal structure; Mn3+ Jahn-Teller distorsionSugiliteMineralogyCrystal structureBlock (periodic table)

description

Crystal with the composition SrMn 2 [Si 2 O 7 ](OH) 2 .H 2 O were found in a sugilite, serandite-pectolite rich sample from the Wessels Mine, Kalahari, South Africa. The crystal structure of the nex compound with space group Cmcm, a = 6.255(1), b = 9.034(2), c = 13.397(2) A, Z = 4 was determined from X-ray single-crystal data (R = 0.048). The structure is of the lawsonite type where Al is completely replaced by Mn 3+ and Ca by Sr. [Mn 3+ O 6 ] octahedra forming edge-sharing chains parallel to a exhibit a Jahn-Teller distortion with four short and two long Mn 3+ -O distances. Sr is in eight-fold coordination and H 2 O is disordered on a split position. Together with orientite, macfallite, ruizite, and okhotskite the new compound belongs to a family of structures which have the fundamental building block [Mn 3+ (OH) 2 (SiO 4 ) 2 ] and 6 x 9 A cell dimensions in common

yearjournalcountryeditionlanguage
1992-02-13
https://www.bib.irb.hr/370893