• Chemistry: Na2ZrSi3O9 - 2H2O; Hydrated Sodium Zirconium Silicate.
  • Class: Silicates
  • Subclass: Cyclosilicates
  • Uses: Only as a mineral specimen.
  • Specimens

Catapleiite is a rather rare zirconium mineral. It forms in alkaline rocks and rare rocks known as agpaites which are igneous rocks of unusual concentrations. They are characterized by high concentrations of alkali metals especially sodium and low concentrations of silicon and aluminum. They are feldspar and feldspathoid rich and being low in silicon, contain little or no quartz. Agpaite pegmatites contain unusual minerals because they originate with unusual elements. Elements such as beryllium, zirconium, titanium, niobium, barium, strontium, thorium and rare earth metals are all found in the compositional mix that represents this rock type.

There exists agpaite in several places around the world, but by far the most famous are the ones at the Kola Peninsula in Russia, Narsarsuk, Greenland and the one above all the rest, the mines of Mount Saint Hilaire, Quebec, Canada. Catapleiite is just one of the rare minerals that can form in these silica starved, unique chemical environments. Other minerals coming from these unique localities include leifite, synchysite, serandite, elpidite, aegirine, arfvedsonite, eudialyte and analcime to name a few.

Catapleiite is dimorphous with the mineral gaidonnayite. Dimorphous means that both minerals have the same chemistry, but they have different structures. Catapleiite is monoclinic (pseudohexagonal) while gaidonnayite is orthorhombic. Catapleiite is also in a series with the mineral calcium catapleiite in which the sodium of catapleiite is replaced with a calcium ion instead. In a series, the structure remains the same, but the chemistry is different.

Catapleiite although quite rare, forms at several localities around the world. But it is the magnificent specimens of rosette clusters found only at Mount Saint Hilaire that demonstrate the mineral's true beauty. Its rarity, beauty, unusual chemistry, classic locality and cool name make catapleiite a great addition to a mineral collection.


  • Color is blue, gray, pale yellow, yellowish-brown, reddish or colorless.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is monoclinic; 2/m.
  • Crystal Habits include pseudohexagonal plates or lamellar masses. Splendid rosettes are also known. Twinning is common.
  • Cleavage is perfect in one direction.
  • Hardness is 5 - 6.
  • Specific Gravity is 2.8
  • Streak is white.
  • Associated Minerals include feldspars, feldspathoids and Sphene among many rare species.
  • Notable Occurrences include Magnet Cove, Arkansas, USA; Madagascar; Laven, Langesundfjord, Norway and Mount Saint Hilaire, Quebec.
  • Best Field Indicators are crystal habit, locality and color.
CATAPLEIITE specimens:
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CATAPLEIITE specimen cat-1
$ 55.00
Dims: 1.7 x 1.2 x 1.2" (4.3 x 3.0 x 3.0 cm)
Wt: 16.2 g
Mount Saint Hilaire, Quebec, Canada
At least 5 intergrown Catapleiite blades rest on the mottled white host rock of this piece. These blades range in size from 0.3 x 0.1 x 0.1" (8 x 3 x 3 mm) to 1.0 x 0.6 x 0.2" (2.5 x 1.5 x 0.5 cm) and appear to be in very good condition, though the largest crystal shows some noticeable breakage on one edge. Their hexgaonal tabular form is slightly warped due to restricted growing space, but is still definable. Each crystal has generally well-defined edges and clean faces that possess a pearly-to-vitreous luster- the largest crystal shows odd, concentric hexagonal striations on its largest face. All are colorless, transparent, and moderately to very clear, containing both internal fractures and a few cloudy inclusions. The host rock on which they rest is made up of thousands of intergrown crystals of what I believe is a zeolite mineral that I cannot identify covering a darker mineral (I do not know what that one is, either).
no photo
cat-1 ($ 55.00)
Mount Saint Hilaire, Quebec, Canada
CATAPLEIITE specimen cat-2
$ 70.00
Dims: 1.0 x 0.8 x 0.4" (2.5 x 2.0 x 1.0 cm)
Wt: 11.0 g w/ base
Mount Saint Hilaire, Quebec, Canada
At least 4 intergrown Catapleiite crystals make up the bulk of this thumbnail specimen. These crystals do not exceed 0.1" (3 mm) in thickness or 0.6" (1.5 cm) in diameter, and show slight to considerable damage, depending on the crystal. Their hexagonal bladed form is very good- all edges are well-defined and all faces are clean and possess a pearly luster. Each face also has a subtle iridescence, of which I do not know the cause. Their color is a creamy-white and they are translucent. The Catapleiites are accompanied by what appear to be a few tiny chabazite crystals, according to their rhombohedral form. There is also a small amount of a black mineral present which may be epidote, but I cannot be certain. These two minerals make up the "host rock" of the specimen, which is hot-glued onto an acrylic base.
no photo
cat-2 ($ 70.00)
Mount Saint Hilaire, Quebec, Canada
CATAPLEIITE specimen cat-3
$ 85.00
Dims: 0.6 x 0.4 x 0.2" (1.5 x 1.0 x 0.5 cm)
Wt: 9.7 g w/ specimen box
Mount Saint Hilaire, Quebec, Canada
This small thumbnail specimen basically consists of a single Catapleiite crystal to which is attached a small amount of associated host rock. The crystal appears to be in excellent condition, showing very little damage, and has excellent hexagonal bladed form. Its edges are well-defined and its faces are generally clean, except where it intersects with the sparse host material. The crystal is colorless, transparent and quite clear, and has a pearly luster. Some of the surrounding material has the appearance of albite or another feldspar, whereas the black material that is present makes me think of nepheline. The piece is affixed inside of a plastic specimen box with an adhesive putty.
no photo
cat-3 ($ 85.00)
Mount Saint Hilaire, Quebec, Canada
CATAPLEIITE specimen cat-4
$ 85.00
Dims: 2.5 x 1.6 x 0.7" (6.3 x 4.0 x 1.9 cm)
Wt: 2.0 oz. (56 g)
Mount Saint-Hilaire, Quebec, Canada
Stacked pseudohexagonal Catapleiites make up most of the mass of this specimen. These blades are in very good condition- nearly all of the damage present appears to be old- and have dimensions nearly equal to the length and width of the entire specimen. Their monoclinic, pseudohexagonal form is very good and is reminiscent of the mica group. These blades have a beige coloration and a bright adamantine to vitreous luster, and are opaque to dimly translucent. They are accompanied by many small aegirines, most of which are broken, and a large section of worn, crystalline nepheline or augite.
no photo
cat-4 ($ 85.00)
Mount Saint-Hilaire, Quebec, Canada
CATAPLEIITE specimen cat-5
$ 85.00
Dims: 1.2 x 1.1 x 0.9" (3.0 x 2.8 x 2.3 cm)
Wt: 0.6 oz. (18 g) w/ base
Mount Saint-Hilaire, Quebec, Canada
Several Catapleiite blades are intergrown to form this thumbnail specimen. These blades are generally in good condition, though a few of them are obviously broken and incomplete. The largest complete blades have a diameter of about 0.4" (1.0 cm) and all show excellent monoclinic pseudohexagonal form; one of the broken blades shows definite twinning. All have a color that ranges from colorless to beige, and all have a bright pearly to vitreous luster; most show a faint iridescence on their surfaces. A few tiny, broken Natrolites also rest on the piece, which is hot-glued to a flat acrylic base.
no photo
cat-5 ($ 85.00)
Mount Saint-Hilaire, Quebec, Canada
CATAPLEIITE specimen cat-6
$ 45.00
Dims: 1.1 x 1.0 x 0.8" (2.8 x 2.4 x 2.0 cm)
Wt: 0.4 oz. (11 g) w/ base
Mount Saint-Hilaire, Quebec, Canada
Two Catapleiite blades make up the bulk of this thumbnail piece. The larger of these blades is incomplete (though not freshly damaged) and has 1.1 x 0.6 x 0.2" (2.8 x 1.6 x 0.6 cm); the smaller one is grows off of one of the large faces of the other, is complete, and measures about 1 mm in diameter. Both show excellent monoclinic pseudohexagonal form and are colorless, transparent and moderately clear, as they contain inclusions of other minerals. Their luster is pearly to vitreous and they are accompanied by many small, white feldspathoid blades and what appear to be tiny, heavily weathered aegirines. The piece is hot-glued onto an acrylic base.
no photo
cat-6 ($ 45.00)
Mount Saint-Hilaire, Quebec, Canada


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