Igneous Rock (Dolerite/Diabase)

Preseli Bluestone

The Stonehenge Stone

Dark Blue-Gray
Blue-Green with White Spots

Quick Facts

FormulaVariable (plagioclase + pyroxene + olivine)
SystemN/A (rock, multiple minerals)
LusterDull to Sub-vitreous
StreakN/A (rock)
TransparencyOpaque
Sp. Gravity2.90-3.00
Mohs Hardness
6

Formation & Origin

Preseli bluestone is the name given to the spotted dolerite (diabase) from the Preseli Hills in Pembrokeshire, Wales - the same rock used to build the inner circle of Stonehenge, located 240 kilometers away in Wiltshire, England.

The geological fact that Stonehenge's bluestones were transported from Wales to Salisbury Plain approximately 5,000 years ago is one of the most remarkable achievements in prehistoric engineering. Each bluestone weighs 2-5 tons. How Neolithic people moved 80+ massive stones across 240 kilometers of rugged terrain remains one of archaeology's most debated questions - theories range from human hauling to glacial transport to water routes.

The rock itself is a dolerite (medium-grained igneous rock) with distinctive white spots of altered feldspar or pyroxene crystals. It formed as an igneous intrusion approximately 450 million years ago (Ordovician period). Recent archaeological work has pinpointed the exact quarry sites in the Preseli Hills, including Carn Goedog and Craig Rhos-y-felin.

Identification Guide

Preseli bluestone is identified as a dark blue-gray dolerite with characteristic white spots (feldspar phenocrysts). At hardness 6, it's moderately hard. The spotted texture is its most distinctive visual feature.

Distinguish from regular dolerite/diabase (may lack the distinctive spots), basalt (finer-grained, different texture), and gabbro (coarser-grained). Genuine Preseli bluestone from the Welsh hills has the specific spotted texture associated with the Stonehenge material.

Spotting Fakes

Preseli bluestone is a specific rock from a specific location - the Preseli Hills of Wales. Any dark igneous rock can be marketed as 'bluestone.' Genuine Preseli material should show the characteristic white spots and come from verified Welsh sources. The geological connection to Stonehenge is the value driver - without provenance, it's just spotted dolerite.

Cultural & Metaphysical Traditions

Presented as cultural traditions, not scientific evidence

Preseli bluestone's connection to Stonehenge gives it extraordinary metaphysical significance. Practitioners associate it with ancient wisdom, sacred geometry, and the mystery of Neolithic spiritual practice. Druidic traditions (both historic and modern) consider it a stone of power and connection to ancestral knowledge. The fact that prehistoric people considered this rock worth transporting 240 kilometers - an enormous undertaking - suggests it held deep spiritual significance even 5,000 years ago.

Where It's Found

United Kingdom - Preseli Hills, Pembrokeshire, Wales

The only source, same rock as Stonehenge's bluestones

Price Guide

Entry$5-15 small tumbled
Mid-Range$15-50 polished or raw
Collector$50-200 larger specimens with documentation

Good to Know

๐Ÿ’Ž

Scratch test: At hardness 6, Preseli Bluestone resists scratching from a knife but can be scratched by quartz. Best for pendants and earrings rather than rings.

๐ŸŒ

Sources: Found at only one location on Earth - United Kingdom. Supply is inherently limited.

โš–๏ธ

Heft test: Preseli Bluestone has average mineral density (2.90-3.00). It feels about as heavy as you'd expect from a stone its size.