• 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.
MORDENITE specimens:
(hover for more info)
MORDENITE specimen mrd-1
$ 54.00
Dims: 7.8 x 4.2 x 3.3" (19.8 x 10.7 x 8.4 cm)
Wt: 1 lb., 14.8 oz. (874.0 g)
New Water Mountains, near Eagle Eye, La Paz County, Arizona, U.S.A.
This odd cabinet-sized specimen consists of a pale brown host rock that is partly coated by several patches of extremely fine, fibrous Mordenite crystals. These crystals are much finer than human hair and are so thin that they look like cotton wool or spider webs. They are flexible, and though there is some noticeable damage to a few of the patches, individual fibers are far too small to study even under 15x magnification. They grow out of patches of more massive, white material that is most likely more Mordenite, and there are small spots of a pale green coloration that are evidence of a thin layer of unknown material between the massive layer and the base rock.
no photo
mrd-1 ($ 54.00)
New Water Mountains, near Eagle Eye, La Paz County, Arizona, U.S.A.
MORDENITE specimen mrd-2
$ 37.00
Dims: 3.7 x 3.3 x 1.9" (9.4 x 8.4 x 4.8 cm)
Wt: 5.92 oz. (167.8 g)
Prineville, Oregon, U.S.A.
This specimen consists of several crusts of massive Mordenite out of which extend countless superfine Mordenite needles. These needles are generally in very good condition, though a few patches are noticeably crushed, and achieve lengths of up to 0.6" (1.5 cm) or greater. As their diameter measures far less than 1 mm (each is considerably thinner than a human hair), their orthorhombic form is impossible to study without high magnification. All appear to be compacted at their bases, but radiate and separate into individual fibers towards their terminations. Their white color likewise darkens to a pale gray towards their terminations, and all appear to possess a pearly luster. A small amount of a dull, moderately pale brown host rock is present- it looks a lot like dried mud.
no photo
mrd-2 ($ 37.00)
Prineville, Oregon, U.S.A.
MORDENITE specimen mrd-3
$ 25.00
Dims: 0.6 x 0.6 x 0.6" (1.5 x 1.5 x 1.5 cm)
Wt: 12.3 g w/ specimen box
Kalama, Cowlitz County, Washington, U.S.A.
At least 10 small Mordenite blades rest on the brown host rock of this small thumbnail specimen. Several are broken and mostly incomplete, but at least 4 or 5 are intact and in good condition. The largest of these intact blades has a diameter of 0.3" (8 mm) and like all of the others, has a rather badly-defined orthohrombic bladed form- though their edges are sharp, they are quite uneven, as are their faces. All have a white coloration and a dull, nearly matte luster. The dark brown host rock is covrered with a very fine druse of what I believe are almost microscopic quartz crsytals. It is affixed inside a plastic specimen box with an adhesive putty.
no photo
mrd-3 ($ 25.00)
Kalama, Cowlitz County, Washington, U.S.A.
MORDENITE specimen mrd-4
$ 25.00
Dims: 1.2 x 0.7 x 0.5" (3.0 x 1.8 x 1.2 cm)
Wt: 0.4 oz. (10 g) w/ specimen box
Skookumchuck Dam, near Bucoda, Thurston County, Washington, U.S.A.
This rather interesting thumbnail specimen consists of a section of thin crust from which extends a dense matte of countless Mordenite fibers. Though some crushing damage is evident, the matte is in very good condition. Each fiber is microscopically thin and pearly in luster. Though individual fibers are likely colorless and transparent, their intense density gives the matte a white color. The piece is hot-glued into a plastic thumbnail box.
no photo
mrd-4 ($ 25.00)
Skookumchuck Dam, near Bucoda, Thurston County, Washington, U.S.A.


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