Recommended nomenclature of epidote-group minerals

Abstract

The key cation-sites M3 and A1 (and, in principle, M2) determine the root name. In both clinozoisite and allanite subgroups no prefix is added to the root name if M1 = Al. The prefixes ferri, mangani, chromo, and vanado indicate dominant Fe 3+ , Mn 3+ , Cr 3+ , and V 3+ on M1, respectively. In the dollaseite subgroup no prefix is added to the root name if M1 = Mg. Otherwise a proper prefix must be attached; the prefixes ferro and mangano indicate dominant Fe 2+ and Mn 2+ at M1, respectively. The dominant cation on A2 (other than Ca) is treated according to the Extended Levinson suffix designation. This simple nomenclature requires renaming of the following approved species: Niigataite (old) = clinozoisite-(Sr) (new), hancockite (old) = epidote-(Pb) (new), tweddillite (old) = manganipiemontite-(Sr) (new). Minor modifications are necessary for the following species: Strontiopiemontite (old) = piemontite-(Sr) (new), androsite-(La) (old) = manganiandrosite-(La) (new). Before a mineral name can be assigned, the proper subgroup has to be determined. The determination of a proper subgroup is made by the dominating valence at M3, M1, and A2 expressed as M 2+ and or M 3+ , not by a single, dominant ion (i.e., Fe 2+ , or Mg, or Al). In addition, the dominant valence on O4: X -or X 2-must be ascertained. The dominant trivalent cation on M3 determines the name, whereas the A2 cation appearing in the suffix has to be selected from among the divalent cations. (2) Allanite and dollaseite subgroups: For the sites involved in the charge compensation of a heterovalent substitution in A2 and O4 (i.e. M3 in the allanite subgroup; M3 and M1 in the dollaseite subgroup), identification of the relevant end-member formula must take into account the dominant divalent charge-compensating octahedral cation (M 2+ ) and not the dominant cation in these sites.Formal guidelines and examples are provided in order to determine a mineral "working name" from electron-microprobe analytical data.

Epidote-(Sr), CaSrAl2Fe3+(Si2O7)(SiO4)(OH), a new mineral from the Ananai mine, Kochi Prefecture, Japan

“…Although Miyajima et al (2003) have already reported the CaSrAl 2 Fe 3+ (Si 2 O 7 )(SiO 4 )(OH) composition as the most Sr -rich niigataite, little has been known about the mineralogical feature of the Sr -analogue of epidote. We also found the Sr -bearing epidote in the Ananai mine, Kochi Prefecture, Japan, and identified this mineral to be similar to epidote -(Sr) proposed by Armbruster et al (2006). The new mineral data and its name "epidote -(Sr)" have been approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association (#2006 -055).…”

“…The Sr -analog of epidote, CaSrAl 2 Fe 3+ (Si 2 O 7 )(SiO 4 ) (OH), has been proposed as a possible member of the clinozoisite subgroup minerals by Armbruster et al (2006). Although Miyajima et al (2003) have already reported the CaSrAl 2 Fe 3+ (Si 2 O 7 )(SiO 4 )(OH) composition as the most Sr -rich niigataite, little has been known about the mineralogical feature of the Sr -analogue of epidote.…”

“…Epidote -group minerals, which have the general formula of A 2 M 3 (T 2 O 7 )(TO 4 )(OH), are divided into three subgroups: clinozoisite, allanite, and dollaseite subgroups (Armbruster et al, 2006). In the clinozoisite subgroup minerals, divalent cations occupy ninefold -coordinated A(1) and tenfold -coordinated A(2) sites, and trivalent cations occupy sixfold -coordinated M(1), M(2), and M(3) sites.…”

Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

“…Major element concentrations are shown as weight % oxides (wt.%). Amphibole nomenclature is after Hawthorne et al (2012), pyroxene nomenclature is after Morimoto (1989) and epidote nomenclature follows Armbruster et al (2006). Mineral abbreviations are from Whitney and Evans (2010).…”

Micro-structural and compositional variations of hydrothermal epidote-group minerals from a peralkaline granite, Corupá Pluton, Graciosa Province, South Brazil, and their petrological implications

“…The minerals in this group fit the general formula A (OH,F), where the cations with octahedrycal and cubic or greater coordination fill in the M and A structural sites, respectively. The epidote-group mineral nomenclature, as approved by the IMA, was proposed by Armbruster et al (2006), who recognized three main subgroups: clinozoisite, allanite, and dollaseite. , and Mn 2+ are essential cations in M (1) and/ or M (3) .…”