Ultra Rare Turquoise Gunheath China Clay Mine Cornwall UK Specimen

Genuine Ultra Rare Turquoise – Gunheath China Clay Mine, St Austell, Cornwall

This Ultra Rare Turquoise specimen from Gunheath China Clay Mine, St Austell, Cornwall, England, UK, is a genuine and highly collectible British mineral. Carefully selected for quality and locality significance, the photograph provided shows the exact specimen you will receive. Please refer to the images for full sizing and scale details.

Your crystal includes a Certificate of Authenticity lifetime guarantee generic card confirming its genuine identity and Cornish provenance.

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Mineral Species & Chemical Composition

Turquoise is a hydrated copper aluminium phosphate with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. It belongs to the phosphate mineral group and crystallises in the triclinic crystal system, although crystals are extremely rare. Most turquoise occurs as compact, cryptocrystalline masses, vein fillings or nodular forms.

Mineral Name: Turquoise
Chemical Formula: CuAl₆(PO₄)₄(OH)₈·4H₂O
Mineral Group: Phosphate
Crystal System: Triclinic
Hardness: 5–6 on the Mohs scale
Lustre: Waxy to subvitreous
Transparency: Opaque

The distinctive blue to blue-green colour is produced by copper content, while variations toward green may reflect differing iron levels. Natural matrix veining or host rock inclusions are common and can enhance both geological interest and display appeal.

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Geological Setting – St Austell Granite & China Clay District

Gunheath China Clay Mine lies within the St Austell Granite district, one of Cornwall’s most significant geological regions. The granite intrusion, emplaced during late Variscan tectonic activity, underwent extensive hydrothermal alteration.

China clay (kaolin) deposits formed as feldspar-rich granite altered through interaction with mineral-rich fluids. During this alteration process, phosphate-bearing fluids interacting with copper and aluminium-rich zones created favourable conditions for turquoise formation.

Turquoise from Cornwall is exceptionally rare due to the specific geochemical requirements for its development. It typically forms as a secondary mineral within fractures, cavities or altered granite zones.

Associated minerals in the Gunheath area may include:

• Kaolinite

• Quartz

• Tourmaline

• Fluorite

• Chalcopyrite

This complex hydrothermal environment gives Cornish turquoise strong geological significance.

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Physical Characteristics & Notable Features

This specimen may display:

• Blue to blue-green coloration

• Compact or nodular growth

• Natural matrix attachment

• Subtle surface veining

Turquoise from Gunheath is typically massive rather than crystalline, forming through gradual mineral replacement and cavity infill. Surface texture may range from smooth and waxy to slightly granular depending on formation conditions.

Natural inclusions and host rock remnants are authentic aspects of the mineral’s geological history and contribute to the uniqueness of each piece.

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Collectibility & Cornish Rarity

Cornwall is internationally recognised for its diverse mineralogy, yet turquoise occurrences are scarce within the region. Specimens from Gunheath China Clay Mine are therefore considered highly unusual and desirable among collectors of British minerals.

Collectors value Cornish turquoise for:

• Documented St Austell Granite provenance

• Rare British occurrence

• Distinctive copper phosphate mineralisation

• Strong regional mining heritage

Material from named china clay pits carries both geological and historical interest linked to Cornwall’s world-famous mining industry.

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Authenticity & Presentation

This Ultra Rare Turquoise specimen has been carefully chosen to showcase the character and rarity of Gunheath material. The image provided shows the exact specimen you will receive.

Included with your purchase is a Certificate of Authenticity lifetime guarantee generic card confirming this is a genuine Turquoise specimen from Gunheath China Clay Mine, St Austell, Cornwall, England, UK.

A rare example of Cornish copper phosphate mineralisation, this specimen combines documented locality, geological significance and strong collector appeal in one authentic British mineral piece.