• Chemistry: (Ca, Na2, K2)Al2Si10O24 - 7H2O, Hydrated Calcium Sodium Potassium Aluminum Silicate.
  • Class: Silicates
  • Subclass: Tectosilicates
  • Group: Zeolites
  • Uses: Mineral specimen and chemical filter.
  • Specimens

Mordenite is one of the rarer, but still somewhat more widespread, members of the zeolite group of minerals. Zeolites are a popular group of minerals to collect because they are so beautiful and because they contain such diversity in color, crystal form and rarity (some are very common and easy to collect and some are rare and a pleasure to finally own). Mordenite belongs to this last category.

Zeolites have an openness about their structure that allows large ions and molecules to reside and actually move around inside the overall framework. The structure actually contains open channels that allow water and large ions to travel into and out of the crystal structure. The size of these channels controls the size of the molecules or ions and therefore a zeolite like mordenite can act as a chemical sieve, allowing some ions to pass through while blocking others.

Mordenite forms fine sprays of radial acicular crystal clusters that look like pin-cushions or snowballs. On top of other interesting and beautiful associated minerals, mordenite can be extremely striking. Mordenite is definitely a must have especially for the dedicated zeolite collector.


  • Color is colorless, white, yellow, pink and red.
  • Luster is vitreous to silky and pearly.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is orthorhombic; 2/m 2/m 2/m
  • Crystal Habits include sprays of radial acicular crystal clusters that can remind someone of pin-cushions or snowballs. Individual crystals are prismatic to acicular and striated vertically. Aggregates can be radiating, fibrous, columnar and encrusting.
  • Hardness is 4 - 5.
  • Specific Gravity is approximately 2.1 (very light)
  • Streak is white.
  • Associated Minerals are quartz, calcite, chabazite, natrolite, heulandite, stilbite and other zeolites.
  • Notable Occurrences include Morden (hence the name), Kings Co., Nova Scotia, Canada; Hoodoo Mountains, Wyoming and Arizona, USA; Val dei Zuccanti, Italy and Poona, India.
  • Best Field Indicators are crystal habit, color, low density and associations.
This Site Awarded
Available MORDENITE specimens:
MORDENITE specimen MRD-5
$ 35.00 -50% = $ 17.50
Dims: 4.06x2.83x1.51in (10.31x7.19x3.84cm) .... Wt: 8.9oz (252g) .... Loc: Rat's Nest Claim, Custer County, Idaho, USA
I originally purchased this as a heulandite specimen, as it does have a very fine, nicely presented cluster of heulandite crystals. But the bulk of the specimen is mordenite, mostly as a densely packed mass of fine mordenite crystals, which are nicely exposed along the broken edges of the specimen. Unfortunately, a loupe is required to fully appreciate the mordenite - but you can't miss it.
no photo
$ 17.50
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MORDENITE specimen MRD-6
$ 45.00 -50% = $ 22.50
Dims: 3.14x2.46x1.83in (7.99x6.24x4.66cm) .... Wt: 9.9oz (280g) .... Loc: Rat's Nest Claim, Custer County, Idaho, USA
Another two-for-one specimen of heulandite on mordenite. The heulandite has much nicer crystals, but the specimen is mostly mordentite which superficially just looks like a massive layer of chalk, but a loupe reveals to be a dense growth of extremely fine acicular crystals growing out of a thin layer of some pink mineral which coats the cavities in the host rock.
no photo
$ 22.50
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MORDENITE specimen MRD-7
$ 57.00 -50% = $ 28.50
Dims: 6.12x3.36x2.85in (15.55x8.52x7.25cm) .... Wt: 25.2oz (714g) .... Loc: Rat's Nest Claim, Custer County, Idaho, USA
This interesting heulandite on mordenite specimen contains layers of flat plates of mordenite, revealing both the horizontal plane of the cavity as the mordenite was deposited, plus the fact that water levels shifted as the layers formed. Since the heulandite was deposited both above and below the mordenite, it appears that the heulandite formed after the mordenite, and from a solution that likely differed in chemical composition.
no photo
$ 28.50
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see this List of ALL specimens including SOLD ones


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