Poisonous Rocks?

buckleyJuly 6, 2008

I have a rather small yard in the Denver area where I have hauled in and arranged about 10-15 tons of rhyolite boulders to form a high border/short retaining wall/rock garden area the full width of my yard. I then filled in behind and between the rocks with "planters mix", a sandy loam with compost mixture. The rocks and soil came from the same supplier. As soon as I started watering plants, the rocks began to effloresce salt! (yes, I've tasted it) Most rocks are covered with a powdery residue. Some have a flaky crusty build up, and some even grow little salty "worms" that stick out from the rock. You can wash it off daily and it comes right back. My rocks are now surrounded by 3-6 inch wide halos of salt-encrusted soil, and so far I have 65 dead plants, mostly near the rocks, but more recently some a good distance away from the rocks. The supplier admitted that there are sometimes salt veins that run through the rhyolite, but says it has never been a problem before, and they still recommend their rhyolite for general landscaping. They suggest that I rinse/flood the rocks frequently to wash and leach the salt away and say that the problem will probably go away.

Now I need advice. I don't know if I need a geologist, a master gardener, or a lawyer, but all of my labor and money has gone for nothing. I have killed unkillable plants and contaminated my whole back yard with this salt, and they want me to "give it time"! Has anyone ever heard of salt contaminated rhyolite? Will this go away, or last for years? Isn't this considered toxic, or at least an environmental hazard? I have yet to approach the supplier with the idea of replacing the rocks, soil, and plants, and providing the labor to do it for me. Does this sound like a legitimate lawsuit? I'd love to hear opinions....HELP!

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cynandjon(Z 5/6)

Hi Buckley
I found this info about Rhyolite.

Rhyolite is a light-colored rock with silica (SiO2) content greater than about 68 weight percent. Sodium and potassium oxides both can reach about 5 weight percent. Common mineral types include quartz, feldspar and biotite and are often found in a glassy matrix. Rhyolite is erupted at temperatures of 700 to 850° C.

Below is the link for anyone interested.

Here is a link that might be useful: Rhyolite

    Bookmark   July 7, 2008 at 12:32PM
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leftwood(z4a MN)

I am not even close to being any kind of pseudogeologist, but salt doesn't just wash through the soil, although I am sure it would help. Apparently gypsum reacts in certain soils either with the salt itself or the soil, but the end result is that the salt's adhesion to soil particles is broken and can be washed through more thoroughly.

It might be that the supplier hasn't had any problems because they haven't come across any rhyolite right next to a salt vein until your project. And your rock is more heavily contaminated. Whatever you decide, document, document, document all your problems.

    Bookmark   July 8, 2008 at 1:30AM
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