The facts
What bastite actually is
Mineralogically, bastite is serpentine pseudomorph — Mg₃Si₂O₅(OH)₄ after (Mg,Fe)SiO₃, crystallising in the monoclinic, preserving orthorhombic outlines system.
The colour is caused by green from Fe²⁺; the bronze schiller comes from relict oriented iron-oxide platelets in the original pyroxene. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.55–1.57 (spot), and the specific gravity sits near 2.5–2.6; cleavage is basal parting inherited from the pyroxene.
Where bastite comes from
The recognised sources are Baste, Harz Mountains, Germany and Lizard Peninsula, Cornwall, England.
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How bastite is treated
Untreated, usually waxed on polishing. An old term still current among mineral collectors and lapidaries rather than in laboratory gemmology.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What bastite is confused with
The usual confusions are Bronzite, Hypersthene and Serpentine.
The separation is rarely a matter of opinion: refractive index 1.55–1.57 (spot) and specific gravity 2.5–2.6 settle most of it in a minute, and magnification settles the rest.
What bastite is used for
Bastite is bought by mineral collecting and carving and sculpture — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the specimen or by the block.
Durability and care
Bastite is 3.5–4 on the Mohs scale, with basal parting inherited from the pyroxene cleavage.
Below about 5.5 a stone will be scratched by ordinary household dust, which is largely quartz. That does not make it unusable — it makes it a pendant, an earring or an object rather than a ring worn every day.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What bastite costs
Indicative pricing for bastite is Cabochons 10–40 USD.
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 bastite treated, and how?
Untreated, usually waxed on polishing. An old term still current among mineral collectors and lapidaries rather than in laboratory gemmology.
Where does bastite come from?
Baste, Harz Mountains, Germany and Lizard Peninsula, Cornwall, England. Origin affects price, so we name the locality rather than the country on every quote.
Is bastite hard enough to wear every day?
Not really. At 3.5–4 on the Mohs scale it is softer than the quartz dust in ordinary household dirt, so it scratches with wear. It suits pendants, earrings and objects better than a daily ring.
How much does bastite cost?
Indicatively Cabochons 10–40 USD. 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 bastite confused with?
Most often Bronzite, Hypersthene and Serpentine. A refractive index of 1.55–1.57 (spot) and a specific gravity near 2.5–2.6 separate it quickly.
Related stones
Looking for bastite?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about bastite