Alkali-deficient tourmaline from the Sullivan Pb-Zn-Ag deposit, British Columbia
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Abstract
Alkali-deficient tourmalines are found in albitized rocks from the hanging-wall of the Sullivan Pb-Zn-Ag deposit (British Columbia, Canada). They approximate the Mg-equivalent of foitite with an idealized formula □(Mg2Al)Al6Si6O18(BO3)3(OH)4. Major chemical substitutions in the tourmalines are the alkali-defect type [Na*(x) + Mg*(Y) = □(x) + Al(Y)] and the uvite type [Na*(x) + Al(Y) = Ca(x) + Mg*(Y)], where Na* = Na + K, Mg* = Mg + Fe + Mn. The occurrence of these alkali-deficient tourmalines reflects a unique geochemical environment that is either alkali-depleted overall or one in which the alkalis preferentially partitioned into coexisting minerals (e.g. albite).
Some of the alkali-deficient tourmalines have unusually high Mn contents (up to 1.5 wt.% MnO) compared to other Sullivan tourmalines. Manganese has a strong preference for incorporation into coexisting garnet and carbonate at Sullivan, thus many tourmalines in Mn-rich rocks are poor in Mn (<0.2 wt.% MnO). It appears that the dominant controls over the occurrence of Mn-rich tourmalines at Sullivan are the local availability of Mn and the lack of other coexisting minerals that may preferentially incorporate Mn into their structures.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Alkali-deficient tourmaline from the Sullivan Pb-Zn-Ag deposit, British Columbia |
| Series title | Mineralogical Magazine |
| DOI | 10.1180/minmag.1997.061.409.08 |
| Volume | 61 |
| Issue | 409 |
| Year Published | 1997 |
| Language | English |
| Publisher | Cambridge University Press |
| Contributing office(s) | Geology, Energy & Minerals Science Center |
| Description | 8 p. |
| First page | 853 |
| Last page | 860 |
| Country | Canada |
| Other Geospatial | British Columbia |
| Google Analytic Metrics | Metrics page |