When faceted, the members of the axinite mineral group are usually intensely trichroic, with considerable brilliance and rich brown and purple colors dominating. Although very rare, these gems could make magnificent jewelry stones.
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α = 1.674 - 1.693; β = 1.681 - 1.701; γ = 1.684 - 1.704.
Magnesioaxinite: α = 1.656; β = 1.660; γ = 1.668
Biaxial (-), 2V = 63-80° or more. However, may turn (+) if high in Mg.
Biaxial +, Biaxial -
From the Greek axine for “axe,” alluding to the common wedge shape of its crystals. Ferroaxinite, magnesioaxinite, and manganaxinite refer to the chemical composition of these varieties. Tinzenite refers to the type locality of this variety, Tinzen, Switzerland.
Axinite is found in areas of contact metamorphism and metasomatism.
Axinites form a mineral group, which includes iron (Fe) dominant ferroaxinite, magnesium (Mg) dominant magnesioaxinite, and manganese (Mn) dominant manganaxinite. Tinzenite is an intermediate member between ferroaxinite and manganaxinite.
Most gem-quality axinites are ferroaxinites, but you will likely encounter specimens called simply “axinites.” However, specific gems should ideally be referred to by their composition-specific names or with designations such as “axinite-(Fe).”
Greenish manganaxinite crystals on acicular johannsenite crystals. Field of view 7 mm. Iron Cap Mine, Landsman Camp (Landsman group), Aravaipa, Santa Teresa Mts, Aravaipa District, Graham County, Arizona. Photo and specimen Leon Hupperichs. Licensed under CC By-SA 3.0.
These strongly pleochroic gems can show three colors, depending on the viewing angle, and can have significant brilliance, too. (See the “Pleochroism” section in the Information Table above). With a hardness of 6.5 to 7, axinites of all varieties have “Very Good” wearability grades. This means they can withstand the rigors of use in most jewelry settings. However, these stones have anisotropic hardness. It may vary within a single specimen depending on the gem’s orientation. In addition, they have somewhat brittle tenacity.
Axinites are almost never completely free of clarity flaws, such as feathers and veils. Nevertheless, because of their rarity, these exquisite gems would still command the interest of both gem collectors and jewelry enthusiasts.
Rare magnesioaxinites have demonstrated a slight color change effect. Specimens from Tanzania have shown a pink color under incandescent light and a blue color under fluorescent light. Other changes have also been noted.
Axinite and another rare gemstone, andalusite, have overlapping ranges of body and trichroic colors as well as hardness. However, axinite’s refractive index (RI) range and specific gravity (SG) range exceed those of andalusite.
Axinites with clean clarity over 5 carats are difficult to find and worthy of museum display. Faceted specimens of any type over 10 carats are rare. Material from Baja California will yield gems to about 25 carats. However, if clean, these stones will cut less than 5 carats.
Geological Museum (Natural History Museum, London): 0.78 (magnesioaxinite, Tanzania).
Although resistant to scratching due to their hardness, axinites have good cleavage and brittle tenacity. Avoid jewelry settings where these gems may receive blows.
Although axinites have very good wearability, their inclusions may pose risks if these gems are cleaned in mechanical systems. Have a gemologist examine them, identify any inclusions, and recommend a cleaning method. Since axinites also have some heat sensitivity, avoid boiling or steam cleaning. A soft brush, mild detergent, and warm water can serve as a safe alternative. Consult our gemstone jewelry cleaning guide for more recommendations.