What is the ultimate geological explanation, whether it really exists, for the origin of the zebra rock (also known as zebra stone in Australia)? Could you indicate me the more cited references?
Dear Dr. Folly:
A distinctive reddish brown and white banded sedimentary rock from Kimberley of West Australia was called zebra rock, zebra stone or ribbon stone (Bevan 2002). It is composed of small particles of quartz and sericite, kaolinite and its polymorph, dickite, as well as alunite. Its color banding probably formed by the rhythmic precipitation of hematite- enriched bands during the alteration of the rock by percolating fluids. The zebra rock forms lenses extending for kilometers, within the Late Precambrian Johnny Cake
Shale. It is a fine-grained (anchimetamorphosed) sedimentary rock .
Bevan A.W.R. 2002 Rare Australian ornamental materials - zebra rock
an ornamental stone from the East Kimberley, Western Australia. Australian Mineralogist 21, 165-168.
Best regards
H.G.Dill
Zebra rock is a siltstone, rather than a mineral specimen, although the difference may be lost on many collectors. It is arguably the most commonly collected rock related material from Western Australia, and sold widely internationally. There are several retail outlets for the material also in Kununurra. This entry, and specific localities under it, is to try and address requests for information on Mindat in the recent past about zebra rock.
Zebra rock is often a result of intervening of high organic matter rocks with media of another rocks without any organic indication. It is an alteration processes exists in sedimentary rocks.
Zebra rock is crush mush that shows "self organizing" healing. It reflects overpressurization in a sealed system that has locally failed and is being healed.
Zebra rocks: compaction waves create ore deposits | Scientific Reports (nature.com)
Below is an image showing conjugate patterns of zebra stripes and foliations. I believe it is at the vertex of a "rhombic basin"/pull-apart system.
Here is a link to reports of "zebra rock" in a gold quartz vein from Colorado that I mined once long ago. The stripes are formed by chemical/mineral healing but if ambient pressure builds, say during an earthquake...it can brecciate within the vein. That shock can dump out gold itself to make bonanza material but you don't get the striped pattern unless the system heals itself up nicely. There are reports of zebra rock looking like unidirectional solidification structures (USS's) with one way crystal termination. In Zebra rock...you should get two way termination...I would imagine.
In the big silverton sunnyside mine material below you can see both intact and failed zebra rock material in the same vein at different parts. I would bet it is from the famous 2040 stope, 2150 vein. Been there...well if there is gold...yes that's the good gold vein. Zebra rock ore with gold!...
http://www.turnstone.ca/rom175zr.htm
I think these papers could help you;
They're available on the ResearchGate Server for download.
Check out this link
http://www.minsocam.org/msa/collectors_corner/arc/zebra.htm
I say it is mineralization related to chemical “diffusion” maybe outward from the boundary layer of an overpressured zone.
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