The facts
What stromatolite actually is
Mineralogically, stromatolite is laminated sedimentary structure built by microbial mats trapping and precipitating carbonate - among the oldest evidence of life on Earth — Calcite or dolomite CaCO3 / CaMg(CO3)2, frequently silicified to chert, crystallising in the aggregate system.
The colour is caused by organic carbon and iron oxides producing the dark-and-light lamination. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.486-1.658 carbonate; 1.53-1.54 silicified, and the specific gravity sits near 2.55-2.85; cleavage is carbonate cleavage where unsilicified.
Where stromatolite comes from
The recognised sources are Strelley Pool Chert, Pilbara, Western Australia (approx. 3.4 Ga; protected, collecting prohibited), Cottonwood Canyon, Wyoming, USA (Green River Formation), Bolivia (Cochabamba, Precambrian material widely traded), Morocco and Mauritania and Shark Bay, Western Australia (living examples, fully protected).
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 stromatolite is treated
Untreated; polished and occasionally stabilised. LEGAL: the scientifically important Australian localities are protected - Strelley Pool material cannot be legally collected or exported, and Shark Bay's living stromatolites are a World Heritage site. The commercial trade is dominated by Bolivian and Moroccan material. Much 'stromatolite' in the bead trade is Kambaba stone, which is probably not a stromatolite at all.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What stromatolite is confused with
The usual confusions are Kambaba stone, Banded chert and agate, Landscape marble and Onyx-marble banding.
The separation is rarely a matter of opinion: refractive index 1.486-1.658 carbonate; 1.53-1.54 silicified and specific gravity 2.55-2.85 settle most of it in a minute, and magnification settles the rest.
What stromatolite is used for
Stromatolite is bought by mineral collecting, architecture and interiors, decorative objects and jewellery — 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, by the square metre or by the piece.
Durability and care
Hardness 3-4 (carbonate), 6.5-7 where silicified; cleavage carbonate cleavage where unsilicified. That combination decides what it can safely be set into.
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 stromatolite costs
Indicative pricing for stromatolite is $10-60 per kilogram for Bolivian and Moroccan slabs; scientifically documented specimens price as fossils.
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 stromatolite treated, and how?
Untreated; polished and occasionally stabilised. LEGAL: the scientifically important Australian localities are protected - Strelley Pool material cannot be legally collected or exported, and Shark Bay's living stromatolites are a World Heritage site. The commercial trade is dominated by Bolivian and Moroccan material. Much 'stromatolite' in the bead trade is Kambaba stone, which is probably not a stromatolite at all.
Where does stromatolite come from?
Strelley Pool Chert, Pilbara, Western Australia (approx. 3.4 Ga; protected, collecting prohibited), Cottonwood Canyon, Wyoming, USA (Green River Formation), Bolivia (Cochabamba, Precambrian material widely traded), Morocco and Mauritania and Shark Bay, Western Australia (living examples, fully protected). Origin affects price, so we name the locality rather than the country on every quote.
Is stromatolite hard enough to wear every day?
Not really. At 3-4 (carbonate), 6.5-7 where silicified 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 stromatolite cost?
Indicatively $10-60 per kilogram for Bolivian and Moroccan slabs; scientifically documented specimens price as fossils. 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 stromatolite confused with?
Most often Kambaba stone, Banded chert and agate, Landscape marble and Onyx-marble banding. A refractive index of 1.486-1.658 carbonate; 1.53-1.54 silicified and a specific gravity near 2.55-2.85 separate it quickly.
What is stromatolite used for besides jewellery?
mineral collecting, architecture and interiors and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for stromatolite?
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 stromatolite