『Abstract
　Epidote-group minerals are monoclinic in symmetry and have topology consistent with space group P21/m and the general formula A2M3[T2O7][TO4](O,F)(OH,O). Zoisite is an orthorhombic polymorph of clinozoisite Ca2Al3[Si2O7][SiO4]O(OH) and is thus not considered a member of the epidote-group. Epidote-group minerals are divided into three subgroups. (1) Members of the clinozoisite subgroup are derived from the mineral clinozoisite Ca2Al3[Si2O7][SiO4]O(OH) by homovalent substitutions only. The key cation- and anion-sites are A1 = M²⁺, A2 = M²⁺, M1 = M³⁺, M2 = M³⁺, M3 = ³⁺, O4 = O^2-, O10 =(OH)^-. In other words, the dominant valence as listed above must be maintained. (2) Members of the allanite subgroup are REE-rich minerals typified by the eponymous mineral “allanite”. This subgroup may be derived from clinozoisite by homovalent substitutions and one coupled heterovalent substitution of the type ^A20(REE)³⁺ + ^M3M²⁺→^A2Ca²⁺ + ^M3M³⁺. Thus the valences on the key sites are: A1 = M²⁺, A2 = M³⁺, M1 = M³⁺, M2 = M³⁺, M3 = M²⁺, O4 = O^2-, O10 = (OH)^-. (3) Members of the dollaseite subgroup are REE-rich minerals typified by the eponymous mineral “dollaseite”. This subgroup may be derived from clinozoisite by homovalent substitutions and two coupled heterovalent substitutions of the type ^A2(REE)³⁺ + ^M3M²⁺→^A2Ca²⁺ + ^M3M³⁺ and ^M1M²⁺ + ^O4F^-→^M1M³⁺ + ^O4O^2-. Thus the valences on the key sites are: A1 = M²⁺, A2 = M³⁺, M1 = M²⁺, M2 = M³⁺, M3 = M²⁺, O4 = F^-, O10 = (OH)^-.
　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 = A1. The prefixes ferri, mangani, chromo, and vanado indicate dominant Fe³⁺, Mn³⁺, Cr³⁺, and V³⁺ 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 Fe²⁺ and Mn²⁺ 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 M²⁺ and or M³⁺, not by a single, dominant ion (i.e., Fe²⁺, or Mg, or Al). In addition, the dominant valence on O4: X^- or X^2- must be ascertained. [M²⁺]A2＞0.50, [M³⁺]M3＞0.50 → clinozoisite subgroup, [M³⁺ + M⁴⁺]A2＞0.50, [M²⁺]M3＞0.50 → allanite subgroup, {[M²⁺]M3+M1−[M³⁺ + M⁴⁺]A2}＞0.50 and [X^-]O4＞0.5 → dollaseite subgroup. Coupled heterovalent substitutions in epidote-group minerals require a special application of the so-called 50％ rule in solid-solution series. (1) Clinozoisite subgroup: 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 (M²⁺) 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.

Key-words: Nomenclature; epidote-group minerals; clinozoisite; allanite; dollaseite.』

1. Introduction
　1.1. Some obvious problems
　1.2. Objectives
2. Historical synopsis
　2.1. Epidote and clinozoisite
　2.2. Zoisite
　2.3. Piemontite, strontiopiemontite, and tweddillite
　2.4. “Tawmawite” and mukhinite
　2.5. Hancockite and niigataite
　2.6. REE-rich epidote-group minerals
　2.7. Epidote modules in polysomatic series
3. Recommended nomenclature
　3.1. Definition of an epidote-group mineral
　　Definition
　　Annotation
　3.2. Definition of subgroups
　3.3. Role of U⁴⁺ and Th⁴⁺ in the allanite and dollaseite subgroups
　3.4. Derivation of mineral names
　3.5. Definition of new species of epidote-group minerals
　3.6, Assigning subgroups and mineral names to solid-solution members
　　3.6.1. Assigning subgroups
　　3.6.2. Assigning mineral names
　　　3.6.2.1. Clinozoisite subgroup
　　　3.6.2.2. Allanite and dollaseite subgroups
4. Deriving a mineral name from electron-microprobe analytical data
　4.1. Formula normalization
　4.2. Determination of negative charges
　4.3. Charge-balance of the empirical formula
　4.4. Assignment of ionic species to the various key sites
　4.5. Subgroup and root name
　4.6. Usage of the term “pistacite”
　4.7. Usage of the term “oxyallanite”
5. Metamictization
6. Appendix
Acknowledgement
References

Table 2. Clinozoisite subgroup: accepted mineral species (in bold) along with selected examples of recommended names for possible new members of epidote-group minerals.

Name	Old name	A1	A2	M1	M2	M3	O4	O10
Clinozoisite Clinozoisite-(Sr)* Clinozoisite-(Pb)	Niigataite	Ca Ca Ca	Ca Sr Pb	Al Al Al	Al Al Al	Al Al Al	O O O	OH OH OH
Epidote Epidote-(Pb)* Epidote-(Sr)	Hancockite	Ca Ca Ca	Ca Pb Sr	Al Al Al	Al Al Al	Fe3+ Fe3+ Fe3+	O O O	OH OH OH
Ferriepidote Ferriepidote-(Sr) Ferriepidote-(Pb)		Ca Ca Ca	Ca Sr Pb	Fe3+ Fe3+ Fe3+	Al Al Al	Fe3+ Fe3+ Fe3+	O O O	OH OH OH
Vanadoepidote Vanadoepidote-(Sr) Vanadoepidote-(Pb)		Ca Ca Ca	Ca Sr Pb	V3+ V3+ V3+	Al Al Al	Fe3+ Fe3+ Fe3+	O O O	OH OH OH
Mukhinite Mukhinite-(Sr) Mukhinite-(Pb)		Ca Ca Ca	Ca Sr Pb	Al Al Al	Al Al Al	V3+ V3+ V3+	O O O	OH OH OH
Tawmawite**		Ca	Ca	Al	Al	Cr3+	O	OH
Chromotawmawite		Ca	Ca	Cr3+	Al	Cr3+	O	OH
Piemontite Piemontite-(Sr)* Piemontite-(Pb)	Strontiopiemontite	Ca Ca Ca	Ca Sr Pb	Al Al Al	Al Al Al	Mn3+ Mn3+ Mn3+	O O O	OH OH OH
Manganipiemontite Manganipiemontite-(Sr)*	Tweddillite	Ca Ca	Ca Sr	Mn3+ Mn3+	Al Al	Mn3+ Mn3+	O O	OH OH
new root name		Mn2+	Ca	Mn3+	Al	Mn3+	O	OH
* recommended new mineral names for accepted species. ** not a valid species until clear evidence for Cr＞0.5 pfu on M1 or M3 is presented.

Table 3. Allanite subgroup: accepted mineral species (in bold) along with selected examples of recommended names for possible new members of epidote-group minerals.

Name	Old name	A1	A2	M1	M2	M3	O4	O10
Allanite-(Ce), -(La), -(Y) Ferriallanite-(Ce) Vanadoallanite-(REE) Chromoallanite0(REE)		Ca Ca Ca Ca	(REE)3+ Ce3+ (REE)3+ (REE)3+	Al Fe3+ V3+ Cr3+	Al Al Al Al	Fe2+ Fe2+ Fe2+ Fe2+	O O O O	OH OH OH OH
Dissakisite-(Ce), -(La) Ferridissakisite-(REE) Vanadodissakisite-(REE) Manganidissakisite-(REE) Chromodissakisite-(REE)		Ca Ca Ca Ca Ca	(REE)3+ (REE)3+ (REE)3+ (REE)3+ (REE)3+	Al Fe3+ V3+ Mn3+ Cr3+	Al Al Al Al Al	Mg Mg Mg Mg Mg	O O O O O	OH OH OH OH OH
FerriepidoteAndrosite-(REE) (new def.) Manganiandrosite-(La)*, -(Ce)** Ferriandrosite-(REE) Vanadoandrosite-(Ce)** Chromoandrosite-(REE)	androsite	Mn2+ Mn2+ Mn2+ Mn2+ Mn2+	(REE)3+ (REE)3+ (REE)3+ Ce3+ (REE)3+	Al Mn3+ Fe3+ V3+ Cr3+	Al Al Al Al Al	Mn2+ Mn2+ Mn2+ Mn2+ Mn2+	O O O O O	OH OH OH OH OH
New root names		Ca Ca Mn2+ Mn2+	(REE)3+ (REE)3+ (REE)3+ (REE)3+	Al Fe3+ Al Al	Al Fe3+ Al Al	Mn2+ Fe2+ Mg2+ Fe2+	O O O O	OH OH OH OH
* recommended new mineral names for accepted species. ** approved by CNMMN (Cenki-Tok et al., 2006): vanadoandrosite-(Ce) has originally been approved as vanadio-androsite-(Ce).

Table 4. Dollaseite subgroup: accepted mineral species (in bold) along with selected examples of recommended names for possible new members of epidote-group minerals.

Name	A1	A2	M1	M2	M3	O4	O10
Dllaseite-(Ce)	Ca	Ce3+	Mg	Al	Mg	F	OH
Khristovite-(Ce) Ferrokhristovite-(REE) Manganokhristovite-(REE)	Ca Ca Ca	Ce3+ (REE)3+ (REE)3+	Mg Fe2+ Mn2+	Al Al Al	Mn2+ Mn2+ Mn2+	F F F	OH OH OH
New root name	Ca	(REE)3+	Mg	Al	Fe2+	F	OH
New root name	Mn2+	(REE)3+	Mg	Al	Mn2+	F	OH