Axinite
Axinite is not an IMA species but a group: axinite-(Fe), -(Mn), -(Mg) and tinzenite. Triclinic axe-head crystals, hardness 6.5 to 7, density 3.18 to 3.43.
Axinite is not a single mineral species but a group name. The IMA lists Axinite-(Fe), Axinite-(Mn) and Axinite-(Mg), which the Handbook calls ferroaxinite, manganaxinite and magnesioaxinite, and the Handbook files tinzenite in the same group. All are triclinic calcium aluminium borosilicates in axe-shaped crystals, hardness 6.5 to 7, density 3.18 to 3.43.
In short
- No mineral called plain axinite is on the September 2026 IMA-CNMNC Master List. A search for axinite returns three names, Axinite-(Fe), Axinite-(Mg) and Axinite-(Mn); tinzenite is listed separately, and the Handbook of Mineralogy files all four under Axinite group. A label reading axinite is a group determination.
- The Handbook and the IMA use different names: ferroaxinite is Axinite-(Fe), manganaxinite is Axinite-(Mn) and magnesioaxinite is Axinite-(Mg). The IMA formulas are exactly double the Handbook's, Ca4Fe2Al4[B2Si8O30](OH)2 against Ca2FeAl2BSi4O15(OH); the formula masses differ by a factor of 2.000000.
- The Handbook's group notes amount to a naming rule: calcium above 1.5 per formula unit and iron above manganese is ferroaxinite; manganese above iron is manganaxinite; calcium below 1.5 with manganese dominant is tinzenite; magnesium dominant is magnesioaxinite. Applied by script to the six analyses on the four sheets, it returns each sheet's own name six times out of six.
- Cornwall is on the ferroaxinite sheet: on Roscommon Cliff and in the Botallack mine, St. Just, the first localities it names. Across the four sheets the only other British Isles entry is Calliagh, Co. Monaghan, Ireland, for manganaxinite.
- One of the four sheets records fluorescence: magnesioaxinite, red-orange in LW UV, duller red in SW UV. The other three say nothing (ligature-aware search, since two of these sheets render fl as a stray glyph).
| Handbook name | IMA name | Handbook formula | IMA formula | IMA status, year, country | Hardness | Density (meas.) |
|---|---|---|---|---|---|---|
| Ferroaxinite | Axinite-(Fe) | Ca2Fe2+Al2BSi4O15(OH) | Ca4Fe2+2Al4[B2Si8O30](OH)2 | Renamed; 1968 s.p.; France | 6.5 to 7 | 3.25 to 3.28 |
| Manganaxinite | Axinite-(Mn) | Ca2Mn2+Al2BSi4O15(OH) | Ca4Mn2+2Al4[B2Si8O30](OH)2 | Renamed; 2004 s.p.; Germany | 6.5 to 7 | 3.314 |
| Magnesioaxinite | Axinite-(Mg) | Ca2MgAl2BSi4O15(OH) | Ca4Mg2Al4[B2Si8O30](OH)2 | Renamed; 1975-025; Tanzania | about 6.5 | 3.178 |
| Tinzenite | Tinzenite | (Ca,Mn2+,Fe2+)3Al2BSi4O15(OH) | Ca2Mn2+4Al4[B2Si8O30](OH)2 | Redefined; 2016 s.p.; Switzerland | 6.5 | 3.355 to 3.433 |
| Axinite | Not on the list | — | — | Group name only | 6.5 to 7 | 3.178 to 3.433 |
Is axinite a mineral species? No, it is a group of four
First check: the IMA list. Searching the September 2026 IMA-CNMNC Master List for axinite returns exactly three entries: Axinite-(Fe), renamed by special procedure in 1968, type country France; Axinite-(Mg), IMA 1975-025, Tanzania; and Axinite-(Mn), renamed by special procedure in 2004, Germany. Tinzenite, Ca2Mn2+4Al4[B2Si8O30](OH)2, is listed under its own name as redefined in 2016, Switzerland. There is no entry for axinite alone.
Second check: the Handbook. There is no axinite sheet. Four sheets are filed under Axinite group, under older names: ferroaxinite, manganaxinite, magnesioaxinite and tinzenite. The mapping is in the table above. The Handbook's names are the ones on most labels written before the renaming, and they are still clear; the IMA forms are the current ones.
This page is filed under axinite deliberately, because that is the word on the label and the word collectors search for, as with scapolite, which this site treats the same way. None of the four axinite sheets is in this site's 176-sheet reference set, and no sheet in that set mentions axinite; the figures here come from the four group sheets themselves.
Which axinite is mine? The Handbook's naming rule, tested
The four sheets' Mineral Group fields, read together, give a rule. Ferroaxinite: Ca > 1.5 per formula unit, Fe > Mn. Manganaxinite: Ca > 1.5, Mn > Fe. Tinzenite: Ca < 1.5, Mn > Fe. Magnesioaxinite's sheet adds no condition, but its name is for dominant magnesium in the composition.
A worked test on the sheets' own analyses. Divide each oxide by its formula mass (SiO2 60.083, CaO 56.077, FeO 71.844, MnO 70.937, MgO 40.304, from standard atomic weights), scale to 4 silicon as in the Handbook's formula, and apply the rule. Ferric iron is left out, since it substitutes for aluminium.
- Durango, Mexico (ferroaxinite sheet): Ca 1.96, Fe 0.55, Mn 0.13, Mg 0.19 → ferroaxinite.
- Rosebery district, Tasmania (ferroaxinite): Ca 1.96, Fe 0.83, Mn 0.21, Mg 0.09 → ferroaxinite.
- Babbitt, Minnesota (manganaxinite): Ca 1.86, Mn 0.95, Fe 0.26 → manganaxinite. The sheet's own formula, on a different basis, prints Ca1.85 Mn0.94 Fe0.26.
- Arusha district, Tanzania (magnesioaxinite): Ca 2.11, Mg 0.94, Mn 0.03 → magnesioaxinite.
- Tinzen, Switzerland (tinzenite): Ca 1.31, Mn 1.76 → tinzenite; the sheet prints Mn1.77 Ca1.32.
- Gambatesa mine, Italy (tinzenite): Ca 1.40, Mn 1.57, Mg 0.13 → tinzenite.
Six analyses, six correct names. The practical point is the one the rule makes obvious: the name depends on a chemical analysis. Colour does not settle it. Ferroaxinite's sheet lists clove-brown, brown, plum-blue, pearl-gray, manganaxinite's honey-yellow, clove-brown, brown, blue, so a brown or blue axe-head crystal could be either. Unanalysed, axinite or axinite group is the honest label; how to label and catalogue a mineral collection covers the form.
Why the IMA formula is twice the Handbook's
The Handbook writes ferroaxinite as Ca2Fe2+Al2BSi4O15(OH). The IMA writes Axinite-(Fe) as Ca4Fe2+2Al4[B2Si8O30](OH)2. Every subscript is doubled, and on standard atomic weights the formula masses are 570.11 and 1140.22: the same mineral, the same proportions, a different formula unit.
Tinzenite is the one where the two sources differ in substance. The Handbook writes it (Ca,Mn2+,Fe2+)3Al2BSi4O15(OH), a mixed site; the IMA formula, halved, is CaMn2+2Al2BSi4O15(OH), fixing calcium at one and manganese at two. The Tinzen analysis above, Ca 1.31 and Mn 1.76 per four silicon, carries more calcium than the IMA ideal of one. Both formulas are shown in the table, attributed.
Boron is a small fraction by mass. The ideal formulas work out at 6.11% B2O3 for ferroaxinite, 6.12% for manganaxinite and 6.46% for magnesioaxinite, which are the calculated columns on the three sheets to the hundredth. Two of the four Occurrence fields, manganaxinite's and magnesioaxinite's, name boron metasomatism.
Axinite from Cornwall, and where the fine crystals come from
The ferroaxinite sheet opens its distribution with Cornwall: on Roscommon Cliff and in the Botallack mine, St. Just. It says there are many localities even for fine crystals, and names Bourg d’Oisans, Isère, France; the Maderantal, Uri, Switzerland; extraordinary crystals from the Puiva deposit in the Subpolar Urals, and Zlatoust; Skardu, Pakistan; the Obira and Toroku mines in Japan; Coarse Gold, Yreka and New Melones Lake in California and Elkhorn, Montana; Hope, British Columbia, and the Moneta mine, Timmins; Trinidad, Baja California; and Vitória da Conquista, Bahia. The largest crystals it records reach 20 cm.
Manganaxinite's list is shorter and headed a few verified localities: St. Andreasberg in the Harz, Calliagh in Co. Monaghan, Monte Pu in Liguria, Franklin in New Jersey, and others in the USA, Canada and Japan. Magnesioaxinite was originally found as a rough gemstone, blue, from an unrecorded locality in the Arusha district of Tanzania, and is also known from London Bridge, New South Wales, and Luning, Nevada. Tinzenite is from near Tinzen in the Val d’Err, Graubünden; the Cassagna and Gambatesa mines in Liguria; and Akatore, New Zealand.
Its company is the calc-silicate assemblage. Ferroaxinite's associates include prehnite, andradite, zoisite, actinolite, datolite, tourmaline, vesuvianite, calcite and quartz. Against the hard green-to-brown silicates it is found with, the axe-head shape and triclinic habit are the field clues: epidote (hardness 6 to 7, density 3.38 to 3.49) and vesuvianite (6 to 7, 3.32 to 3.43) overlap it in hardness and lie close to it in density, against 3.178 to 3.433 across the group. The rest of this reference section is indexed at the species index. There is no catalogue here and nothing here is offered for sale; the wanted list is the only commercial route.