Green Tourmaline Gunheath China Clay Pit Cornwall Genuine Crystal with Hand Signed Premium Certificate of Authenticity

Genuine Green Tourmaline – Gunheath China Clay Pit, Cornwall, England

This Green Tourmaline specimen from Gunheath China Clay Pit, Stenalees, Treverbyn, Cornwall, is a genuine British mineral example carefully selected for its crystal form, colour and locality importance. The photograph provided shows the exact specimen you will receive. Please refer to the images for full sizing details and accurate scale.

This crystal includes a fully hand-signed Premium Certificate of Authenticity confirming its genuine origin and mineral identification.

Mineral & Geological Classification – Green Tourmaline (Elbaite Variety)

Green Tourmaline is typically a variety of Elbaite, a complex boron silicate mineral belonging to the tourmaline supergroup. Its general chemical formula is Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄, though composition can vary depending on trace elements.

Mineral Group: Tourmaline Supergroup
Common Species: Elbaite (Lithium-rich tourmaline)
Crystal System: Trigonal
Hardness: 7–7.5 on the Mohs scale
Lustre: Vitreous
Transparency: Transparent to translucent

The green colour is typically caused by trace elements such as iron or chromium within the crystal lattice. Tourmaline crystals are well known for their elongated prismatic growth habit, often displaying vertical striations along the crystal faces.

Cornwall Locality – Gunheath China Clay Pit

Gunheath China Clay Pit is part of the renowned Cornubian granite region of Cornwall, an area internationally recognised for its complex mineralogy and historic mining heritage. The region’s granitic intrusions, formed during the Variscan orogeny in the late Carboniferous to early Permian periods, created conditions favourable for pegmatite and hydrothermal mineral formation.

Green tourmaline from this locality forms within granitic pegmatites and associated mineralised veins. Pegmatites are coarse-grained igneous rocks that crystallise from residual magmatic fluids enriched in rare elements such as lithium, boron and fluorine. These conditions are ideal for the growth of well-formed tourmaline crystals.

Associated minerals in Cornish pegmatites may include quartz, feldspar, mica, cassiterite and other tin-bearing minerals, reflecting Cornwall’s long-standing association with tin mining.

Crystal Characteristics & Notable Traits

Green tourmaline typically forms elongated, vertically striated prismatic crystals with triangular or rounded cross-sections. Key characteristics may include:

• Distinct vertical growth striations

• Transparent to translucent crystal zones

• Rich green to deep forest-green colouring

• Vitreous surface lustre

Natural inclusions, zoning or minor surface contacts are part of the crystal’s geological formation and enhance its authenticity. Colour zoning may occur where trace element concentrations varied during growth.

Tourmaline also exhibits pleochroism, meaning the colour may appear slightly different when viewed from different angles under light.

Geological Significance & Collectibility

Cornish tourmaline specimens are highly regarded among mineral collectors due to the region’s geological importance and historic mining legacy. The Gunheath China Clay Pit locality adds further desirability due to its association with granite-hosted pegmatite systems.

This specimen represents a classic example of British pegmatite mineralisation and makes an excellent addition to a mineral cabinet, educational geological collection or display setting.

Because this is a genuine natural specimen, each crystal displays unique features shaped by its growth environment. The photograph shows the exact piece you will receive.

Authenticity & Presentation

This Green Tourmaline specimen has been carefully chosen for colour, crystal form and locality significance. Included with your purchase is a fully hand-signed Premium Certificate of Authenticity confirming its genuine origin from Gunheath China Clay Pit, Stenalees, Treverbyn, Cornwall.

Combining classic Cornish granite geology with the striking prismatic form of tourmaline, this Green Tourmaline specimen offers mineral authenticity, locality importance and collector appeal in one carefully selected crystal.