Pond and Other Products Menu

Natural Bentonite Clay
Origin, mineralogy and properties

Bentonite Formation - Millions of years ago, during the Cretaceous period, the western United States experienced extensive volcanic activity due to the tectonic convergence of the North American and Pacific plates. During long periods of eruptions, immeasurable amounts of ash were disgorged into the prevailing easterly winds as the Pacific plate was forced under the North American plate deep into the earth’s crust. Over millions of years, the ash was repeatedly deposited in the mineral rich Mowry sea and interbedded with eroded silts and sediments. Slowly, the glass component of the ash was chemically altered in these low energy marine environments and consolidated into distinct layers of clay, often associated with Zeolite beds, marl, sandstone as well as shale and mudstone.

As plate drift continued, the North American plate was lifted and folded into mountains, typified by the Big Horn Mountains of Wyoming. The Mowry sea drained and ash deposition subsided as the clay / silt formations were heaved upwards. The Black Hills and the Big Horn mountains were two areas thrust up during this period. These areas were eroded and weathered over time, exposing numerous clay beds that are commercially mined today.

Definition - The term "Bentonite" is generally applied to the colloidal clays originally associated with the Cretaceous Benton Shale outcrops near Fort Benton, Wyoming. In the late 1880’s, the "clay of a thousand uses " was first called Taylorite, after William Taylor; one of the first commercial producers of the product in the Rock River area. Finding that name already taken, the clay was renamed for the Benton formation in which the outcrop was found, i.e. Bentonite.

Mineralogy – Bentonite is not itself a mineral name, but more correctly, it is a smectite clay composed primarily of the mineral Montmorillonite. Montmorillonite is a three layer mineral formed of several layers of tetrahedron and octahedron sheets, electrostatically held together by isomorphic interlayer cations. As the electrostatic attraction is low, exposure to polar fluids will cause the formation of a monomolecular lattice of water between the silicate layers. The basis behind bentonite swelling is that several layers of water dipoles can form into weak "stacked" tetrahedral structures, causing the silicate layers to separate - this is termed intercrystalline swelling.

Particle Charge - Each crystal of Montmorillonite has a large net negative charge. Thus it tends to attract any positive ions (cations), such as Calcium or Sodium ions, to its surface. If the majority of these cations are Sodium, it is commonly referred to as a Sodium Bentonite (Montmorillonite). If the majority of the ions on the clay surface are Calcium, it is referred to as a Calcium Bentonite (Montmorillonite). The net negative charge is located inside the crystal itself. Therefore, cations tend to be attracted to the surface of the particle in an effort to neutralize the charge. The edge of the crystal has a few positive charges thus attracting negatively charged ions or molecules. **

We sell Calcium Bentonite exclusively

Typical chemical analysis of Goldfish Koi Pond Powder®:

Particle size: .0035 inches or 88 microns passing through a #200 screen.

65 different trace minerals have been identified in this essential substance.

The difference in chemical composition between the bentonite compound and the mineral montmorillonite is due to the extra elements and trace elements absorbed by the volcanic ash

**Detailed chemical description