Zeolite Answer

Zeolites have many useful purposes. They can perform ion exchange, filtering, odor removal, chemical sieve and gas absorption tasks. The most well known use for zeolites is in water softeners. Calcium in water can cause it to be “hard” and capable of forming scum and other problems. Zeolites charged with the much less damaging sodium ions can allow the hard water to pass through its structure and exchange the calcium for the sodium ions. This process is reversible.

In a similar way zeolites can absorb ions and molecules and thus act as a filter for odor control, toxin removal and as a chemical sieve. Zeolites can have the water in their structures driven off by heat with the basic structure left intact. Then other solutions can be pushed through the structure. The zeolites can then act as a delivery system for the new fluid. This process has applications in medicine, livestock feeds and other types of research.

Zeolites added to livestock feed have been shown to absorb toxins that are damaging and even fatal to the growth of the animals, while the basic structure of the zeolite is biologically neutral. Aquarium hobbyists are seeing more zeolite products in pet stores as zeolites make excellent removers of ammonia and other toxins. Most municipal water supplies are processed through zeolites before public consumption. These uses of zeolites are extremely important for industry, although synthetic zeolites are now doing the bulk of the work.

Zeolites have basically three different structural variations.

• There are chain-like structures whose minerals form acicular or needle-like prismatic crystals, ie natrolite.
• Sheet-like structures where the crystals are flattened platy or tabular with usually good basal cleavages, ie heulandite.
• And framework structures where the crystals are more equant in dimensions, ie Chabazite.

A zeolite can be thought of in terms of a house, where the structure of the house (the doors, windows, walls and roof) is really the zeolite while the furniture and people are the water, ammonia and other molecules and ions that can pass in and out of the structure. The chain-like structures can be thought of like towers or high wire pylons. The sheet-like structures can be thought of like large office buildings with the sheets analogous to the floors and very few walls between the floors. And the framework structures like houses with equally solid walls and floors. All these structures are still frameworks (like the true tectosilicates that zeolites are).

These variations make the zeolite group very diverse, crystal habit-wise. Otherwise zeolites are typically soft to moderately hard, light in density, transparent to translucent and have similar origins. There are about 45 natural minerals that are recognized members of the Zeolite Group. Industrially speaking, the term zeolite includes natural silicate zeolites, synthetic materials and phosphate minerals that have a zeolite like structure. The complexity of this combined group is extensive with over 120 structural variations and more are being discovered or made every year. Collecting zeolites can be very enjoyable and fulfilling.

Amethyst Galleries’ Mineral Gallery

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Related posts:

1. Zeolite: The Versatile Mineral
2. Zeolite Mineral History & Properties