The discovery of bazzite [Be3Sc2Si6O18] in the granites at Baveno, Italy, dates back to 1915, just a few years after the discovery in Norway of thortveitite, the first known scandium mineral (1911). In 1982 two new scandium minerals, cascandite [CaScSi3O8(OH)] and jervisite [NaScSi2O6] were discovered as additional rarities at Baveno. Owing to the increased activity of collectors, a number of additional finds of bazzite have resulted; similarly, other scandium minerals were recognized to be present, among which thortveitite (Orlandi, 1990) and scandiobabingtonite [Ca2FeScSi5O14(OH)] (Orlandi et al., 1998), the former sometimes affording interesting blue, Mn-bearing specimens (Gramaccioli et al., 2000b). On considering all these discoveries, five of the nine scandium minerals known so far occur at Baveno, which is the type locality for four of them. However, scandium phosphates such as kolbeckite [ScPO4·2H2O] and pretulite [ScPO4] which are relatively diffuse in nature are absent. A possible reason for such a situation is linked to the particular process of formation of these minerals at Baveno, which most probably involves disruption of REE/Sc fluoride complexes following the deposition of relatively abundant fluorite and zinnwaldite from the solutions; there is marked similarity with the Norwegian locality of Heftetjærn, Tørdal, where fluorite is common and many of the Sc-bearing species are the same as at Baveno.
Scandium minerals in the miaroles of granite at Baveno, Italy
ORLANDI, PAOLO
2004-01-01
Abstract
The discovery of bazzite [Be3Sc2Si6O18] in the granites at Baveno, Italy, dates back to 1915, just a few years after the discovery in Norway of thortveitite, the first known scandium mineral (1911). In 1982 two new scandium minerals, cascandite [CaScSi3O8(OH)] and jervisite [NaScSi2O6] were discovered as additional rarities at Baveno. Owing to the increased activity of collectors, a number of additional finds of bazzite have resulted; similarly, other scandium minerals were recognized to be present, among which thortveitite (Orlandi, 1990) and scandiobabingtonite [Ca2FeScSi5O14(OH)] (Orlandi et al., 1998), the former sometimes affording interesting blue, Mn-bearing specimens (Gramaccioli et al., 2000b). On considering all these discoveries, five of the nine scandium minerals known so far occur at Baveno, which is the type locality for four of them. However, scandium phosphates such as kolbeckite [ScPO4·2H2O] and pretulite [ScPO4] which are relatively diffuse in nature are absent. A possible reason for such a situation is linked to the particular process of formation of these minerals at Baveno, which most probably involves disruption of REE/Sc fluoride complexes following the deposition of relatively abundant fluorite and zinnwaldite from the solutions; there is marked similarity with the Norwegian locality of Heftetjærn, Tørdal, where fluorite is common and many of the Sc-bearing species are the same as at Baveno.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
