Tinzenite

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Formula: Ca₂Mn²⁺₄Al₄[B₂Si₈O₃₀](OH)₂
Sorosilicate (Si₂O₇ groups), borosilicate, axinite group, manganese-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.355 to 3.433 measured, 3.455 calculated
Hardness: 6½ to 7
Colour: Lemon-yellow, orange, red
Common impurities: Ti,Mg,Ba,Na,K,H₂O
Environments

Pegmatites
Metamorphic environments
Hydrothermal environments

Tinzenite occurs in pegmatites, quartz veins and metamorphosed manganese-bearing rocks (Dana, Mindat). Associated minerals include calcite, quartz, rhodochrosite, rhodonite and braunite (HOM, Mindat).

Localities

At Klučov, Třebíč District, Vysočina Region, Czech Republic, tinzenite has been found in an NYF granite pegmatite (Mindat).

The Molinello Mine, Ne, Genoa, Liguria, Italy, is a small, abandoned mine. The manganese ore is a stratabound braunite ore, with the manganese thought to have originated from hydrothermal vents. The rocks were exposed to greenschist metamorphic conditions, and to extensive hydrothermal influence, both while deposited during the rifting of the Tethys Ocean and during later orogenies (Mindat).
Fine tinzenite specimens from veins up to 20 cm thick and several meters long have been found in the past, and in the summer of 2023 superb tinzenite specimens were discovered, forming lenticular (biconvex) crystals up to a few millimeters in size, grouped tightly into bulbous mounds and rosettes, and these in turn rest in seams in quartz matrix with multicolored spottings of other species including saneroite, braunite, ganophyllite and rhodochrosite. The tinzenite is an appealing, bright, peachy yellow-orange colour (Minrec 55.1.110).
Image

At Akatore Creek, Clutha District, Otago Region, New Zealand, tinzenite occurs in quartz veins in chert of the greenschist facies (HOM).

The type locality is Parsettens Alp, Tinizong, Surses, Albula Region, Grisons, Switzerland.

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