The facts
What kambaba Stone actually is
Kambaba Stone is classified as silicified microgranular igneous or volcaniclastic rock with orbicular green-and-black rings; often sold as a fossil stromatolite, which recent petrographic work does not support, with the composition Quartz and feldspar with chlorite, amphibole and iron oxides. It crystallises in the aggregate system.
Colour comes from chlorite and amphibole for the dark green-black rings; the orbicular texture is igneous spherulitic, not biological, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.54 approx. (spot). Specific gravity around 2.60-2.85. Cleavage: none. Those three numbers separate it from most of what imitates it.
Where kambaba Stone comes from
Kambaba Stone is produced at Mahajanga and Antsiranana Provinces, Madagascar and South Africa (material sold under the same name).
The locality is part of the description, not a footnote — two stones of the same weight from two of these places are not the same stone.
How kambaba Stone is treated
Untreated, occasionally resin-stabilised. The commercially important point: it is marketed almost universally as a 3-billion-year-old fossil stromatolite, and the petrographic evidence points instead to an orbicular igneous rock. Neither the age claim nor the fossil claim should be repeated as fact. Madagascar has intermittently restricted raw mineral export. Not CITES.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What kambaba Stone is confused with
In the trade kambaba Stone is most often mistaken for, or substituted by, Genuine stromatolite (which has real sedimentary lamination), Nebula stone, Ocean jasper or Green rhyolite.
The separation is rarely a matter of opinion: refractive index 1.54 approx. (spot) and specific gravity 2.60-2.85 settle most of it in a minute, and magnification settles the rest.
What kambaba Stone is used for
Demand for kambaba Stone comes from jewellery, carving and sculpture and decorative objects, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the carat, by the block or by the piece.
Durability and care
Hardness 6-7; cleavage none. That combination decides what it can safely be set into.
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 kambaba Stone costs
As a guide, kambaba Stone trades around $4-15 per kilogram rough; cabochons $8-50.
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 kambaba Stone treated, and how?
Untreated, occasionally resin-stabilised. The commercially important point: it is marketed almost universally as a 3-billion-year-old fossil stromatolite, and the petrographic evidence points instead to an orbicular igneous rock. Neither the age claim nor the fossil claim should be repeated as fact. Madagascar has intermittently restricted raw mineral export. Not CITES.
Where does kambaba Stone come from?
Mahajanga and Antsiranana Provinces, Madagascar and South Africa (material sold under the same name). Origin affects price, so we name the locality rather than the country on every quote.
Is kambaba Stone hard enough to wear every day?
Yes. At 6-7 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 kambaba Stone cost?
Indicatively $4-15 per kilogram rough; cabochons $8-50. 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 kambaba Stone confused with?
Most often Genuine stromatolite (which has real sedimentary lamination), Nebula stone, Ocean jasper and Green rhyolite. A refractive index of 1.54 approx. (spot) and a specific gravity near 2.60-2.85 separate it quickly.
What is kambaba Stone used for besides jewellery?
carving and sculpture and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for kambaba stone?
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 kambaba stone