Kambaba Jasper from Madagascar
Kambaba jasper also known as crocodile jasper or kambaba stone is a relatively rare material found only in Madagascar. Much of the information about it online is vague and inaccurate so in this article we just talk about facts that we know to be true.
Although often referred to as a mineral kambaba jasper is actually a rock. Like all varieties of jasper it's not made up of one single mineral but of many which is why it's a rock not a mineral.
I was first introduced to kambaba jasper in India many years ago whilst choosing cabochons for our collection of gemstone pendants. I was told the name of this distinctive stone was star galaxy jasper. I soon discovered that was a trade name used by gem cutters in Jaipur and that it was actually called kambaba jasper. The name green stromatolite jasper is also sometimes used. A stromatolite is a rock-like structure that forms in shallow waters from the build up of a group of bacteria called cyanobacteria. Also known as blue-green algae, cyanobacteria have a fossil record which dates back almost three and a half billion years so for this reason kambaba is often reported as being more than three billion years old.
Having researched and written about rocks and minerals for many years I'm well aware that not everything you read about them is accurate. Furthermore despite Google's efforts to wipe it out, there's still a significant problem online with plagiarism. For this reason I always check and double check facts before using them in articles that I write and by doing so have managed to eliminate a great deal of inaccurate information that has been written about kambaba jasper.
Many of the articles have repeatedly been plagiarised and each time the information is rewritten, more facts about the geological composition of this stone are excluded or misinterpreted. After a significant amount of research I found an interesting thread in a forum which although quite old, talks about kambaba jasper in great detail. It was started by someone who asked whether it was a stromatolite and the replies which cover several pages feature arguments both for and against. Having read the thread carefully I found the following comment particularly interesting;
I’ve been sitting on my hands trying to stay out of this debate. There's a lot of hokum and claptrap kicking around concerning this material which has created considerable confusion. “Kambaba Jasper” is an invented name for what was hailed in the fringes of the lapidary world as a new material but it isn’t, it's a relatively newly-discovered exposure of an already known material. It has been studied by experts and isn’t stromatolitic or even sedimentary at least not in the samples that have been analysed.
The EPI (Institut für Edelstein Prufüng) or Institute for Gemstone Testing in Germany published a detailed report in one of its bulletins but unfortunately they're only available to members and are only published in German. Nevertheless paraphrasing a bit from their findings, thin-section and X-Ray diffraction analyses have shown that the kabamba material is not a type of jasper at all, it’s volcanic, the green groundmass is composed mainly of quartz, pyroxene (aegirine) with orbicles of alkali feldspar embedded with streaky aggregates comprising tiny needles of amphibole (riebeckite to pargasite). The formation is not fully understood but is most likely to be a volcanic rock that has been “overprinted” by a weak metamorphism. In mineral composition it’s very similar to a rock originating in Mexico that’s generally referred to in the lapidary world as “Eldarite” although the colouration is the reverse of the Madagascan material. Eldarite has a dark groundmass and pale orbical patterns and Kabamba Jasper has a pale groundmass and dark orbicles. Eldarite is also known in America as “Nebula Stone” since after being polished, the patterns resemble nebulae in outer space. The two rocks are nevertheless sufficiently similar from a mineralogical perspective that the EPI recommends the names “Eldarite” and “Kambaba” (with its several spelling variations) should be regarded as synonyms. They also advise that the name “Kabamba Jasper” should be replaced by "Kabamba Stone." (this is the original thread)
Kambaba Jasper | Photo; Marco Campos-Venuti
The thread had been closed for some time so I asked in a different forum relating to rocks and minerals whether anyone could shed any light on exactly what type of stone kambaba jasper was. One response I received was from mineralogist Marco Campos-Venuti who had spent time working in Madagascar. He explained the confusion over whether it was a stromatolite or not stems from the fact that two totally different materials with very similar names have over time become mixed up. Kambaba or kabamba as it's also known locally, comes from a small area in Madagascar known as Kabamba which lies in the west central Bongolava region. The name is sometimes written as Kambaba.
The stone is an oncolite stromatolite which is a rock-like structure that forms in shallow seas and is built up from bacteria which has over time, been replaced by silica. The other stone which is known as kambaby ocean jasper often abbreviated to ocean jasper, is a variety of orbicular jasper so is formed in a totally different manner. It's neither a stromatolite or even a sedimentary rock and is likely to have been the material that was examined by the Institute of Gemstone Testing in Germany.
With this in mind, it's understandable why information about the two stones has become mixed up. The continuous plagiarism and paraphrasing of other people's articles online has led to a great deal of confusion and inaccuracy. Photos of kambaba jasper and kambaby ocean jasper plus additional information can be found here in this article (scroll down to see the thread).
The stone that I have always known as kambaba jasper or crocodile jasper has distinctive green and black colouration and is used almost exclusively for decorative purposes. Ocean jasper which I'm also familiar with looks very different. Until doing research for this article I was unaware that ocean jasper was correctly known as kambaby ocean jasper and have never heard the name being used.
Kambaba jasper grades 6½ to 7 on Mohs scale of mineral hardness and like so many of the plant and animal species in Madagascar, it cannot be found anywhere else in the world.