Atlantisite: Geological and Mineralogical Overview
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Atlantisite is a distinctive mineral aggregate composed primarily of green serpentine intergrown with purple stichtite. It is most famously found in Tasmania, Australia, particularly at Stichtite Hill near Dundas, a mine operated by Mike and Eleanor Phelan. The stone is sometimes referred to as Tasmanite or stichtite in serpentine. Its striking colour contrast has made it both a subject of geological interest and a popular specimen in collections.
Composition and Formation
Atlantisite is formed through the alteration of ultramafic rocks, particularly serpentinite, where stichtite develops as a secondary mineral. Serpentine provides the green matrix, while stichtite contributes purple inclusions. The combination occurs under metamorphic conditions where chromium-rich environments favour the growth of stichtite. The density of Atlantisite ranges between 2.33 and 2.6 g/cm³, reflecting its mixed mineral composition.
Geological Context
The primary locality in Tasmania is significant because it represents one of the few places globally where serpentine and stichtite coexist in such abundance. The mineralisation is linked to ophiolitic complexes, which are remnants of ancient oceanic crust thrust onto continental margins. These geological settings provide the unique conditions for serpentine alteration and stichtite formation.
Atlantisite typically displays pale to dark green hues with purple patches or veins. It is relatively soft, with serpentine registering 2.5 to 5 on the Mohs scale and stichtite around 1.5. This softness makes it suitable for carving and lapidary work but limits its durability in jewellery.
Cultural and Scientific Significance
The name Atlantisite was inspired by the legendary city of Atlantis, reflecting the stone’s unusual and evocative colours. While often marketed for metaphysical properties, such as promoting emotional healing, inner peace and spiritual connection, its scientific value lies in illustrating mineralogical processes in ultramafic terrains. The coexistence of serpentine and stichtite provides insights into metamorphic reactions, hydration and the role of chromium in mineral formation.
Distribution Beyond Tasmania
Although Tasmania is the most recognised source, similar material has been reported in South Africa, where it is described as stichtite-serpentine. However, Tasmanian Atlantisite remains the type locality and is considered the most characteristic example of this mineral association.
Atlantisite is a rare and visually striking mineral composite that highlights the geological complexity of ultramafic terrains. Its occurrence in Tasmania underscores the importance of local geology in producing unique mineral specimens. Beyond its aesthetic appeal, Atlantisite serves as a valuable example of mineralogical processes involving serpentine alteration and stichtite formation.
References
Geology Science – Atlantisite properties and geology: https://geologyscience.com/minerals/atlantisite
The Crystal Council – Atlantisite meanings and properties: https://thecrystalcouncil.com/crystals/atlantisite
Crystal Vaults – Atlantisite healing properties and uses: https://www.crystalvaults.com/crystal-dictionary/atlantisite
Moonrise Crystals – Atlantisite geology and history: https://moonrisecrystals.com/crystal/atlantisite
Rock Identifier – Atlantisite information: https://rockidentifier.com/minerals/atlantisite