pumice vs. "lava rock"

10 years ago

In an earlier discussion there was some mention of these two components of homemade potting soil. As a geologist I thought I would explain the difference between the two. Pumice, chemically speaking, is equivalent to granite and its fine-grained relative, rhyolite. "Lava rock" is scoria, like pumice a volcanic rock. Its equivalents, chemically, are gabbro and basalt, and relatively speaking is richer in calcium, iron and magnesium; these would be released in trace amounts only. Pumice, on the other hand, is richer in sodium. Either one, in my opinion, is excellent as a component of succulent potting soil, but I notice that pumice comes in a much better size for use! Living in Alabama, I cannot get pumice and find scoria too large to use so I use crushed granite in the soil mixture.

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General Pumice Products

10 years ago

Mosasaur47,

Thanks for posting this, I just wanted to let you know you actually CAN get pumice. My company ships 100% high-quality, very dry horticulture pumice in 4 different sizes right to your front door in 15lb. bags. You can find out more information on our website at www.GeneralPumiceProducts.com (and you can also order on there if you'd like).

Thanks!

Lexi Petelski

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Comments (6)

bikerdoc5968 Z6 SE MI
10 years ago
last modified: 10 years ago
As a follow-up reference this link may be interesting. I have ordered several bags and the product is 110% as described.

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ehuns27 7a PA
10 years ago
I missed the pumice discussion Howard posted so I am glad this was brought up again. I have been wanting to make a pumice mix but haven't found a reputable source online. Thanks for the information!

-Erica
bikerdoc5968 Z6 SE MI
10 years ago
I receive nothing from Lexi and Austin except a great product and the opportunity for people like us who don't have a readily available source for this material to purchase it! I have no problem supporting a business that does as they say.
mosasaur47
Original Author
10 years ago
A better way for me to phrase it is that I have no local source for pumice!
Cali Roberts
3 years ago
So if I was growing something that volcanic rock meal or powder is recommended amendment I can use basalt rock dust instead?

How much sodium is in the pumice powder? I wouldn't want extra salts in my soil.