Sugilite - A Rare Precious Stone

Sugilite is a rare and beautiful gemstone that is known for its vibrant purple color. It is a cyclosilicate mineral, which means that it is made up of silicon dioxide and other elements, such as potassium, sodium, iron, manganese, and aluminum.

Sugilite was first discovered in Japan in 1944. It is named after Ken-ichi Sugi, a Japanese geologist who discovered the mineral. Sugilite is found in a few other locations around the world, including Russia, South Africa, and the United States.

Sugilite is a relatively rare pink to purple cyclosilicate mineral with the complex chemical formula KNa₂(Fe, Mn, Al)₂Li₃Si₁₂O₃₀. Sugilite crystallizes in the hexagonal system with prismatic crystals. The crystals are rarely found and the form is usually massive. It has a Mohs hardness of 6 to 6.5 and a specific gravity of 2.75 to 2.80. It is mostly translucent.

16kg Manganoan Sugilite from Wessels Mine in Northern Cape Province, South Africa Photo: RDCnet CC

Sugilite occurs in bedded manganese deposits as an aegirine-bearing syenite stock in biotite granite. This uncommon cyclosilicate mineral displays violet to purple-red coloring. Sugilite crystallizes in the hexagonal system with prismatic crystals. Although crystal specimens of sugilite are infrequently discovered, those that have been found they are usually very large.

Sugilite is popular in jewelry, in thin sections which can be polished or cut into cabochons and mounted in silver or gold in rings, pendants, and earrings. In the 1980s the gem was heavily promoted on home shopping channels and internet auctions sites.

With a Mohs scale hardness of 5-1/2 to 6-1/2, sugilite is somewhat durable. However, be careful wiping dust from sugilite because household dust contains quartz, which may cause scratches. It is recommended to clean sugilite gemstones by using soapy water, rinsing well and drying with a soft cloth. Ultrasonic cleaners and steamers are not recommended. Always remove any jewelry or gemstones before exercising, cleaning or engaging in physical activities such as sports. Store sugilite gemstones away from other gemstones to prevent scratches, wrapped in soft cloth or placed inside a fabric-lined box.

Occurrence

Sugilite is a relatively rare mineral, and it is only found in a few locations worldwide. The most notable deposits of sugilite are found in South Africa, but it has also been found in other countries, such as Australia, Canada, India, Italy, and Tajikistan.

The Wessels Mine in the Northern Cape Province of South Africa is the primary source of sugilite. This mine produces gem-quality sugilite that is used in jewelry and other decorative items. Other notable deposits of sugilite include the Iwagi Islet in Japan, the Mont Saint-Hilaire pegmatite in Quebec, Canada, and the Madagascan pegmatites.

Formation

Sugilite forms through a complex geological process involving the interaction of various minerals and elements. It is believed to occur in metamorphic environments, where manganese-rich rocks come into contact with silica-rich fluids or solutions.

Sugilite is typically found in association with other manganese-rich minerals, such as rhodonite, pyroxmangite, and spessartine. It is also found in association with other cyclosilicate minerals, such as eudialyte and thulite. The exact formation process of sugilite is not yet fully understood.

Uses of Sugilite

Sugilite is a relatively rare gemstone, and it is often used in jewelry and other decorative items. It is also considered to be a powerful metaphysical stone, and it is said to promote peace, love, and spiritual growth.

Sugilite is also used in some industrial applications. For example, it is used as a component in some types of ceramics and glass.

Properties of Sugilite:

Color is purple, brown to yellow, pale pink and even black.
Luster is vitreous to dull or waxy.
Transparency: Crystals are translucent to opaque.
Crystal System is hexagonal; 6/m 2/m 2/m.
Crystal Habits include rare striated prismatic crystals, but specimens are usually massive.
Cleavage is poor in one direction.
Fracture is subconchoidal.
Hardness is 6 - 6.5
Specific Gravity is approximately 2.75 - 2.80 (average)
Streak is brown.
Associated Minerals include pectolite, poudretteite and polylithionite.
Notable Occurrences include the type locality of Iwagi Island, Shikoku, Japan as well as Mont Saint-Hilaire, Quebec, Canada and most importantly, South Africa.
Best Field Indicators are color, hardness, luster, streak and locality.

See also: 

Star Hollandite Quartz
Chalcanthite: Facts About Chalcanthite
Larimar: The Blue Stones of Atlantis