Description
Lewisian Gneiss Crystal Specimen – One of the Oldest Rocks in the UK
This genuine Lewisian Gneiss crystal specimen is a remarkable piece of British geological history. Sourced from Scotland, Lewisian Gneiss represents some of the oldest exposed rock in the United Kingdom, with origins dating back approximately 2.7 to 3.0 billion years to the Archaean Eon. Owning a specimen of this extraordinary metamorphic rock is like holding a fragment of Earth’s earliest continental crust.
The photograph shows the exact specimen you will receive. Each piece is carefully selected for its character, structure, and visual appeal. Full sizing can be confirmed in the listing photographs.
This crystal is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card.
Geological Background – Archaean Age Metamorphic Rock
Lewisian Gneiss forms part of the Lewisian Complex of northwest Scotland, prominently exposed in the Outer Hebrides, the northwest Highlands, and coastal mainland regions. It is classified as a high-grade metamorphic rock, formed under intense heat and pressure deep within the Earth’s crust during the early formation of the planet’s continental masses.
Gneiss is characterised by its distinctive banded or foliated appearance, created through metamorphic differentiation. These alternating light and dark bands result from the segregation of mineral components during recrystallisation.
The rock represents reworked ancient igneous protoliths, primarily tonalitic, trondhjemitic, and granodioritic compositions that were subsequently transformed during multiple tectonic events.
Mineral Composition & Crystal Characteristics
Lewisian Gneiss is typically composed of:
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Quartz (SiO₂) – hexagonal crystal system
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Feldspar (commonly plagioclase and microcline) – triclinic/monoclinic systems
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Biotite mica – monoclinic system
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Hornblende (in some varieties) – monoclinic system
The light-coloured bands are usually dominated by quartz and feldspar, giving pale grey, white, or pinkish tones. The darker bands often contain biotite mica and amphibole minerals, creating contrasting black or deep brown streaks.
Quartz within the specimen may display vitreous lustre and varying degrees of translucency, while feldspar contributes to the rock’s granular crystalline texture. The interlocking crystal structure reflects slow cooling and deep crustal metamorphism.
Natural variations in patterning, mineral concentration, and band thickness make every specimen unique.
Appearance & Display Qualities
Lewisian Gneiss is valued for its dramatic banding and ancient origin. The visual contrast between light quartz-feldspar layers and darker mica-rich bands gives the stone a striking, textured appearance.
Its naturally rugged surfaces highlight the crystalline matrix and structural foliation, making it an excellent addition to:
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Mineral and crystal collections
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Geological teaching displays
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British rock and fossil collections
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Cabinet curiosities
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Educational study sets
Its immense geological age also makes it a thoughtful and symbolic gift for collectors, students of Earth science, or anyone fascinated by deep time and planetary history.
Formation & Tectonic Significance
Lewisian Gneiss records multiple episodes of metamorphism and deformation, linked to early continental collision and crustal evolution. These rocks predate complex life on Earth and were formed long before the development of modern continents.
Over billions of years, they have endured tectonic uplift, erosion, and glaciation, eventually becoming exposed at the surface. Today, they form some of the most iconic and scientifically important geological outcrops in the UK.
Authenticity & Selection
This specimen is a genuine Lewisian Gneiss crystal from the UK. Each piece is individually selected to ensure quality, structural clarity, and aesthetic appeal. The image shown is of the exact specimen you will receive.
A Certificate of Authenticity lifetime guarantee generic card is included with your purchase.
Please refer to the photographs for full sizing and scale.
A rare opportunity to own a tangible fragment of one of the oldest rock formations in Europe, formed billions of years ago during the earliest chapters of Earth’s history.
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