The following is from Bob Vaiden, geologist with Illinois State Geological
Survey (ISGS) in Urbana:
Hope it helps.

Silt is the hard one to find.  I don't know of any commercial sources, but
it's very common along the Illinois and Mississippi Rivers, where it was
deposited on the land surface by wind as loess.  It's easy to collect from
almost any road cut exposure near the rivers.  Loess is light yellow or tan,
and it can be collected by the bucketfull...but if you don't live near the
rivers, I don't know where you'd easily get it!

As for soils.....if you mean commercial products....the % might be stated on
the package.  Soils "in the wild" have a wide range of sand, silt, and clay

Commercial Peat Moss is presumably (almost?) all organic.  I've never read
the package description on a bag of peat moss!


> -----Original Message-----
> [mailto:[EMAIL PROTECTED]]On Behalf Of Michael Lach
> Sent: Wednesday, October 24, 2001 10:38 AM
> To: CSI Science; CSI ISTA; CSI Gardens
> Subject: [ISTA-talk]Soil Help
> I need some help from some of the earth science/soil science teachers out
> there, and maybe some of the gardeners.
> * I'm trying to like to develop a lesson where students mix
> various amounts
> of sand, silt, and clay. I can purchase sand and clay easily, but I can't
> find silt. Any ideas? (I need mineral particles between 0.002 and
> 0.05 mm in
> diameter.)
> * Does anyone know the general texture (by % of sand, silt and clay) of
> off-the-shelf soil? How much does this vary from product-to-product?
> * Peat moss--like I can purchase at Home Depot--is almost pure organic
> material, right?
> * Does anyone know where to get sieves with a 2 mm grate?
> Thanks.
> -ML
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