The facts
What preseli Bluestone actually is
Preseli Bluestone is classified as spotted dolerite - a medium-grained mafic intrusive rock with white plagioclase-rich spots in a blue-grey ground, with the composition Plagioclase, augite and chlorite, with the white spots being altered plagioclase-rich clots. It crystallises in the aggregate system.
Colour comes from blue-grey from augite and chlorite; the white spots are feldspathic alteration patches, which is also what a laboratory looks at when it is asked whether a colour is natural.
Specific gravity around 2.85-3.05. Cleavage: pyroxene and feldspar cleavage. Those three numbers separate it from most of what imitates it.
Where preseli Bluestone comes from
Preseli Bluestone is produced at Carn Menyn, Carn Goedog and Craig Rhos-y-felin, Preseli Hills, Pembrokeshire, Wales - the documented source of the Stonehenge bluestones.
That is the whole list. A single source makes supply fragile and makes any claim of a second origin worth questioning.
How preseli Bluestone is treated
Untreated. LEGAL: the Preseli outcrops are a Site of Special Scientific Interest inside the Pembrokeshire Coast National Park, and removing stone is prohibited - legitimate material is old field-collected stock gathered before the restrictions, and any vendor claiming fresh Carn Menyn stone should be questioned. Sold heavily on the Stonehenge association, much of it from unrelated Welsh dolerite. Not CITES.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What preseli Bluestone is confused with
In the trade preseli Bluestone is most often mistaken for, or substituted by, Ordinary dolerite and diabase, Other Welsh igneous rocks sold under the name or Gabbro.
Because the material is opaque, refractive index is no help. Specific gravity around 2.85-3.05, hardness of 6, streak and magnification do the work instead.
What preseli Bluestone is used for
Demand for preseli Bluestone comes from mineral collecting, decorative objects, jewellery and carving and sculpture, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the specimen, by the piece or by the carat.
Durability and care
Preseli Bluestone is 6 on the Mohs scale, with pyroxene and feldspar cleavage cleavage.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What preseli Bluestone costs
As a guide, preseli Bluestone trades around $20-100 per kilogram for documented old-stock material; small polished pieces $15-80.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is preseli Bluestone treated, and how?
Untreated. LEGAL: the Preseli outcrops are a Site of Special Scientific Interest inside the Pembrokeshire Coast National Park, and removing stone is prohibited - legitimate material is old field-collected stock gathered before the restrictions, and any vendor claiming fresh Carn Menyn stone should be questioned. Sold heavily on the Stonehenge association, much of it from unrelated Welsh dolerite. Not CITES.
Where does preseli Bluestone come from?
Carn Menyn, Carn Goedog and Craig Rhos-y-felin, Preseli Hills, Pembrokeshire, Wales - the documented source of the Stonehenge bluestones. That is the only commercial source.
Is preseli Bluestone hard enough to wear every day?
Yes. At 6 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does preseli Bluestone cost?
Indicatively $20-100 per kilogram for documented old-stock material; small polished pieces $15-80. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is preseli Bluestone confused with?
Most often Ordinary dolerite and diabase, Other Welsh igneous rocks sold under the name and Gabbro. Since the material is opaque, separation relies on specific gravity near 2.85-3.05, hardness and magnification.
What is preseli Bluestone used for besides jewellery?
mineral collecting, decorative objects and carving and sculpture. Each of those trades buys it in a different form and a different unit.
Related stones
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