Sugilite: Properties, Facts and Photos

What is Sugilite?

Sugilite is a rare, distinctive mineral known for its striking purple colour. The intensity can vary depending on the concentration of chemical elements, particularly manganese and iron.

Sugilite was discovered in Japan in 1944. In 1976, it was named after Professor Ken-ichi Sugi, the eminent petrologist who discovered it.

The greenish-yellowish-brown stone he discovered was visually quite different to the purple sugilite found many years later in South Africa.

The mineral he found in Japan was believed to be a variety of eudialyte. With eudialyte already being a known mineral, the stone was not believed to be a new find.

It was another thirty-two years before sugilite was finally classified as a mineral in its own right. 

In 1973, a new source of material came to light in the Kalahari Manganese Fields, Southern Kalahari Desert, South Africa.

The size of the deposit dwarfed anything found previously, and the quality of the sugilite was far superior. The vast majority came from the Wessels Mine, although smaller quantities were also found in the adjacent N'Chwaning Mine.

Sugilite was once known as luvulite, although the name is now very rarely used.'Sugilite' is often pronounced with a soft 'g' as in the word 'genius'. It should, however, be pronounced with a hard 'g' as in 'gold'. This is because the surname of the person after whom it was named is pronounced in this way.

Geology of Sugilite

The chemical composition of sugilite includes potassium, sodium, lithium and aluminium.

It crystallises in masses and also forms individual crystals, although they're extremely rare. Minerals that crystallise with a 'massive' crystal habit form one large, shapeless mass. The crystals have no visible external shape or form.

Most sugilite and certainly the finest grade, comes from the Kalahari Manganese Field, Northern Cape, South Africa. The largest known manganese deposit on Earth, the Kalahari Manganese Field, lies among sedimentary rocks more than two billion years old.

The exact age of the deposit is unknown, but it's estimated to be between two and three billion years old. It's believed to have formed during a period of intense volcanic activity, which resulted in the accumulation of manganese-rich minerals in the Kalahari Desert. Over time, it was covered by sediment and preserved until it was discovered in the 1940s.

The Kalahari Manganese Field is much older than the Kalahari Desert itself, which is estimated to be about five million years old. The deposit has been exposed through erosion and other geological processes, making it accessible for mining today.Over the last few years, smaller deposits of gem-grade sugilite have been discovered in Italy, New South Wales, Mount Saint-Hilaire in Canada, and Tajikistan. It has also reportedly been found in India, but the find has not been pursued because of the limited amount present and low grade.

The finest sugilite, often known as gel sugilite, exhibits exceptional colour, but it's exceptionally rare. It's believed to be mostly mined out.

Because sugilite is a rare and highly sought-after mineral, a considerable amount of fake material is in circulation. It's usually produced from a combination of low-grade sugilite and other minerals that may or may not have been artificially coloured.

It can also be a combination of minerals that contain no sugilite at all. Most fake sugilite comes from China.

Article Pictures

The sugilite in the picture at the top of our article is courtesy of Steve Blyskal.

The single polished stone and rough pieces were once part of our collection.

The sugilite from the Wessels mine is in the Harvard Museum of Natural History, Massachusetts, USA. Photo: Stone Mania.