Thulite (sometimes called rosaline) is an opaque, massive pink manganese-bearing variety of the mineral zoisite. Manganese substitutes for calcium in the structure with up to two percent Mn2+. Thulite is often mottled with white calcite and occurs as veins and fracture fillings transecting many types of rock. In mineralogical literature, thulite may sometimes refer to any pink zoisite. Clinothulite is the manganese bearing variety of monoclinic clinozoisite.

Thulite was first discovered at a place called Sauland in Telemark, Norway in 1820. It is named after the mythical island of Thule in the belief that the island is Norway. Thulite is used as a gemstone and carving material in the manufacture of jewellery and ornamental objects.

Thulite is also found in the Austrian Tyrol, in Mitchell County, North Carolina, and in Western Australia. A new, more recent find of high quality thulite was discovered near Riverside in Okanogan County, Washington, USA.


Thulite Properties

Chemical Composition: 
Silicate of calcium and aluminium - Ca2(Al,OH)Al2(SiO4)3
Classification / Type: 
Belongs to the epidote group of minerals.
Colors / Varieties: 
Crystal System / Forms: 
Orthorhombic System
Specific Gravity: 
3.09 - 3.12
Cleavage / Fracture: 
Perfect 1 directional cleavage / Conchoidal fracture.
Optic Character: 
Anisotropic, D.R.; Biaxial positive.
Refractive Index / Birefringence: 
1.691 - 1.700 / 0.009; Range: 1.688 - 1.707
Parallel fibrous canals, crystals, fingerprints.
U.V. Fluorescence: 
Weak orange yellow in longwave.
Cause of Color: 
Treatment (Enhancement): 
Colorless impregnation: With oil or resin to improve clarity.
Simulants (with separation tests): 
Synthetic Sapphire (optic figure, R.I., S.G., inclusions), Synthetic Spinel (optic character), Synthetic Quartz (optic figure, R.I., S.G., pleochroism), Iolite (R.I., S.G., pleochroism), Glass (optic character), Tourmaline (optic figure, R.I., birefringence), Rough Smoky Quartz (S.G., pleochroism)
Geological Occurrence: 
In metamorphic rocks subjected to regional metamorphism.
U.S.A. (North Carolina), Australia.
Cuts & Uses: 
Facetted cuts, cabochon, carving, etc.