What's So Special about Zeolites?

From Crystal Classics 6/16/23:

OUR update today takes us into the world of Zeolites, a group of minerals loved by collectors and of high importance for their industrial applications.  

But first, the Sainte-Marie-Aux-Mines 2023 Mineral & Gem Show is almost upon us, with the professional phase beginning next Wednesday. Full details, including dates and opening times, can be found at the end of this newsletter.

As its name implies, the development and history of the picturesque town of Sainte-Marie-Aux-Mines, surrounded on both sides of the valley by high mountains, have been governed by mining activity since probably the beginning of the 2nd or 3rd century CE. The principle commodity was silver from mines scattered along the length of the Liepvrette River valley, often referred to as the Val d'Argent (Silver Valley). Ian and Diana, together with Debbie, Tom and the Schlegels will be there to welcome you on the Crystal Classics' stand in The Theatre. Here you will see an amazing range of specimens and any requests you have sent to Debbie over the last few months.

Back to zeolites. Unless you grew up in an area rich in zeolites, most of us will probably have been first introduced to this fascinating and incredibly aesthetic group of minerals through those from the Deccan Traps in north western India. Perhaps we better just add, the term zeolite applies to a large group of crystalline aluminosilicates whose complex chemistry and structure makes them microporous, making them highly important as catalysts and adsorbents. My first encounter with zeolites in industry was as the medium used within the coils of a gas chromatograph. Here, the zeolite compound acts as a molecular sieve with the ability to separate out mixed gases for them to be then individually analysed.  To provide some idea, the pore diameters within the structure of a typical zeolite may be between 0.3 and 0.8 nm (0.0000003 to 0.0000008 mm).

For those of us living in the UK, although zeolite minerals can be found in many locations and as fine crystals, the two countries which stand out are Northern Ireland and the west coast of Scotland. Anyone who has visited the beautiful Isle of Skye will know it's a zeolite paradise. Many of the best localities on Skye are on the coast where erosion constantly exposes fresh material. One classic location is the beach at Sgurr nam Boc. On arrival, the zeolite rewards can be great, but it's the getting there which is the difficult bit! Many choose to walk, fine, provided you don't mind a four mile trek from the car followed by a near vertical cliff decent approaching 700 feet! If you think the decent is bad, then consider the 700 ft return climb with a rucksack full of rock! The only other option is by boat, but this is a dangerous venture as the beach is battered by Atlantic waves, often making the sailing or landing impossible. Why are great minerals so often in the trickiest to get-to places!

Today's selection includes both Indian and Scottish material. In northwest India, amazing Zeolites are found throughout the Deccan Traps igneous province, formed from successive eruptions of a massive shield volcano and forming one of the largest volcanic features on Earth. The term Deccan Traps translates as "Southern Steps"; Deccan from the Sanskrit for "southern" and traps from the Swedish for "stairs", as the hills in this region appear like steps crossing the landscape.

From this vast region we have a Cavansite with Stilbite from the Wagholi quarries; a stunning Powellite with Stilbite and two Calcites with Stilbite, one associated with Chalcedony and one with Heulandite.

We have two very different Neptunites with Natrolite from the Dallas Gem mine (aka California State Gem Mine) in San Benito County, California, USA. As you will have already noticed with the previous Powellite (a calcium molybdate), not all species today are Zeolites, but if so, have associated zeolites with them. With these two specimens, the Neptunite is a complex phyllosilicate but is associated with Natrolite.

Representing Scotland are two classics, a Heulandite from Old Kilpatrick in West Dunbartonshire and Harmotome from Strontian in the North West Highlands. Heulandite from Old Kilpatrick is always striking, displaying vivid reddish-orange crystals to 1.2 cm on a matt grey-black basalt matrix. The sharp, chisel-tipped crystals have a bright lustre on both the prism and cleaved faces and as a bonus, this is accompanied with a beautifully handwritten old label. Harmotome is a fairly rare Zeolite, yet is found as superb crystals in the old mines at Strontian, type locality for both Strontianite and the element Strontium. Based on the two accompanying labels, this is an extremely old and historic small cabinet specimen of the zeolite Harmotome. The 9 x 6 cm display face is totally covered with characteristic blocky white Harmotome crystals of up to about 9 mm across, all with a bright glassy lustre.

Making a quick round-up of today's other specimens includes two beauties from the Czech Republic; an Apophyllite with Scolecite from Techlovice in the Decin District and a Calcite with Natrolite from Stri­bro (Mies) in the Plzen Region of Bohemia. Also very well worth a look is a Chabazite with Stilbite-Ca from the Sarbai Deposit at in Kazakhstan; a Rhodochrosite with Stilbite with Pyrite and Quartz from the Madan Ore Field in Bulgaria and a gorgeous Smoky Quartz with Stilbite-Ca from Strzegom in Lower Silesia, Poland.

Finally, and from a mining district you might not readily associate with Zeolites, two very different Apophyllites with Inesite from the Broken Hill mines in New South Wales, Australia. Both specimens are rather stunning to say the least, so make sure you take a closer look.

Many readers will recall the publication of the late Rudy Tschernich's ground breaking book, Zeolites of the World, in 1994. It boosted the enthusiasm of dedicated Zeolite collectors and opened up a whole new world of collecting for many others. At a much more modest level, we hope today's Zeolite update will have a similar effect. Enjoy. For those of us not in Saint Marie, we will return next week bearing precious metals and pseudomorphs, choices of which need to be made this afternoon! Have a great weekend.

from Chat GPT1: Title: Exploring the Versatile Uses of Zeolite Minerals from India's Deccan Plateau


India's Deccan Plateau, renowned for its geological richness, is home to a diverse range of minerals. Among these valuable resources, zeolite minerals stand out due to their exceptional versatility and widespread applications. Zeolites are crystalline aluminosilicate minerals with a unique microporous structure that lends them remarkable properties. The Deccan Plateau's abundant zeolite deposits have been harnessed for numerous industrial, agricultural, and environmental purposes. In this article, we delve into the various uses of zeolite minerals from the Deccan Plateau in India.

  1. Water Filtration and Purification

One of the primary applications of zeolite minerals is in water filtration and purification systems. The microporous structure of zeolites enables them to act as molecular sieves, selectively trapping and removing harmful contaminants from water. Zeolites effectively remove heavy metals, ammonia, nitrate, and other pollutants, making them invaluable for both industrial and domestic water treatment processes. The Deccan Plateau's zeolite deposits have played a crucial role in supplying the nation with high-quality water treatment solutions.

  1. Soil Amendment and Agriculture

Zeolite minerals have significant agricultural applications, particularly as soil amendments. Due to their cation exchange capacity (CEC) and ability to retain water and nutrients, zeolites enhance soil fertility and promote plant growth. By effectively storing and slowly releasing water and essential nutrients, zeolites improve moisture retention, reduce nutrient leaching, and enhance crop productivity. The Deccan Plateau's zeolite-rich soils have contributed to improved agricultural practices, especially in regions where water scarcity and nutrient deficiencies are prevalent.

  1. Animal Feed Additives

The utilization of zeolite minerals as animal feed additives is another important application. Zeolites can bind and detoxify mycotoxins, which are harmful fungal metabolites found in various feed ingredients. By reducing mycotoxin absorption in the digestive tract, zeolites contribute to improved animal health and performance. Furthermore, zeolites can also serve as growth promoters, enhancing nutrient absorption and digestion in livestock. The Deccan Plateau's zeolite reserves have played a pivotal role in ensuring the quality and safety of animal feed in the region.

  1. Gas Separation and Storage

Zeolite minerals exhibit excellent adsorption properties, making them suitable for gas separation and storage applications. The unique pore structure of zeolites allows for the selective adsorption of different gases based on their molecular sizes and polarities. This property has significant implications in the purification of industrial gases and the separation of mixtures such as nitrogen and oxygen. Zeolites also find use in storing gases like hydrogen and natural gas, contributing to advancements in clean energy technologies. The Deccan Plateau's zeolite resources have supported India's endeavors in gas separation and storage solutions.

  1. Catalysis and Petrochemical Industry

Zeolite minerals have proven to be exceptional catalysts due to their high surface area and well-defined porous structure. They are widely used in various catalytic processes within the petrochemical industry, such as cracking, isomerization, and hydrocarbon conversions. The Deccan Plateau's zeolite deposits have contributed to the development of cost-effective catalytic materials and processes, playing a vital role in the growth of India's petrochemical sector.


The zeolite minerals found in the Deccan Plateau of India have established themselves as invaluable resources with diverse applications. From water filtration and soil amendment to animal feed additives and gas separation, zeolites have demonstrated their versatility across various industries. The Deccan Plateau's zeolite reserves have been instrumental in supporting sustainable development and addressing critical challenges in water treatment, agriculture, energy, and petrochemical sectors. As we continue to explore and harness the potential of zeolite minerals, these remarkable resources from the Deccan Plateau will undoubtedly continue to contribute to India's progress and the global scientific community at large.


from Chat GPT2: Exploring the Treasures of the Deccan Plateau: Mineral Specimens from India's Geological Marvel

India's Deccan Plateau, a vast elevated region covering a significant portion of the country's southern peninsula, is not only a geological marvel but also a treasure trove of stunning mineral specimens. With its diverse geology and rich mineral deposits, the Deccan Plateau offers collectors and enthusiasts a captivating glimpse into the Earth's ancient history and the mesmerizing beauty hidden within its rocky embrace. Let us embark on a journey through the geological wonders and remarkable mineral specimens that can be found in this extraordinary region.

The Deccan Plateau is believed to have formed around 65 million years ago through volcanic activity. It is composed of thick layers of basaltic lava flows that were ejected during the Deccan Traps eruption, one of the largest volcanic events in Earth's history. The plateau's geological composition provides a unique environment for the formation and preservation of various minerals, resulting in a remarkable diversity of specimens.

One of the most sought-after minerals from the Deccan Plateau is zeolite. These intricate crystalline structures form in cavities within the volcanic rocks and are known for their delicate beauty. Zeolites such as stilbite, heulandite, and chabazite can be found in abundance, with their soft colors and intricate formations mesmerizing collectors. The vibrant pink and peach hues of stilbite, often accompanied by the sparkle of calcite crystals, make for captivating specimens that are highly prized.

Another mineral that captures the attention of collectors is apophyllite. This transparent to translucent mineral often forms stunning, well-defined crystals that range from colorless to green. Apophyllite crystals can be found in various shapes, including pyramids, cubes, and tabular forms, adding to their aesthetic appeal. These specimens are frequently associated with other minerals such as stilbite and quartz, creating beautiful combinations of colors and textures.

The Deccan Plateau is also renowned for its agates, which are prized for their vibrant colors and intricate banding patterns. Agates are a form of chalcedony, a microcrystalline variety of quartz. The volcanic rocks of the Deccan Plateau provide an ideal environment for the formation of agates, resulting in a wide variety of specimens with captivating patterns and hues. From the rich reds and oranges of carnelian agates to the soothing blues and purples of blue lace agates, the Deccan Plateau offers an exquisite range of these gemstones.

Furthermore, the Deccan Plateau is home to various other minerals such as calcite, quartz, amethyst, and hematite. Each of these minerals exhibits unique characteristics and formations, adding to the allure of the region for mineral enthusiasts. Quartz crystals can be found in a range of colors, from the transparent beauty of rock crystal to the delicate pink of rose quartz. Amethyst, a purple variety of quartz, is also abundant in the region, often occurring in geodes or as clusters of crystals.

The Deccan Plateau's geological wealth extends beyond its mineral specimens. The region's volcanic rocks have been significant in studying Earth's history, particularly the mass extinction event that led to the demise of the dinosaurs. The Deccan Traps eruption coincided with the Cretaceous-Paleogene boundary, and the study of its lava flows has provided valuable insights into the environmental changes that occurred during that period.

For mineral collectors and enthusiasts, the Deccan Plateau is a treasure trove waiting to be explored. Its diverse range of minerals, from zeolites and apophyllites to agates and quartz, offers a feast for the eyes and a glimpse into the Earth's fascinating past. Whether you are an avid collector or simply someone who appreciates the wonders of nature, a visit to the Deccan Plateau in India is sure to leave you in awe of its geological splendor and the exquisite mineral specimens it holds.