Identification guide · Minerals
How to Identify Eudialyte
Eudialyte typically appears pink, red, or brownish-red, occasionally yellow or violet, embedded within a coarse-grained igneous matrix, with a vitreous luster on fresh surfaces. Its streak is white, hardness falls between 5 and 6, and it shows poor to indistinct cleavage, breaking with a conchoidal fracture. It is almost always found intergrown with feldspar, nepheline, and dark sodium-rich pyroxene or amphibole rather than as free-standing crystals. Its association with alkaline igneous rock and distinctive red color make it hard to confuse with anything except garnet, which lacks eudialyte's typical host-rock context.
Eudialyte identification checklist
| Color | Red, Pink, Brownish-red, Yellow, Brown | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous to greasy | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent to translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5–5.5 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Indistinct/poor on {0001} and {1010} | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 2.74–3.1 | Ordinary rock-like heft (specific gravity about 2.92), similar to quartz. |
| Crystal system | Trigonal |
Extra tests for Eudialyte
Glass check. Eudialyte shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Eudialyte look-alikes and how to tell them apart
Both sit near Mohs 5–5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Eudialyte vs Chabazite →
Diaspore is harder (Mohs 6.5–7) than Eudialyte (Mohs 5–5.5), so Diaspore will scratch Eudialyte and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Eudialyte vs Diaspore →
Hessonite is harder (Mohs 6.5–7) than Eudialyte (Mohs 5–5.5), so Hessonite will scratch Eudialyte and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Eudialyte vs Hessonite →
Eudialyte is harder (Mohs 5–5.5) than Heulandite (Mohs 3.5–4), so Eudialyte will scratch Heulandite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
Eudialyte identification FAQ
How can you tell if a rock is Eudialyte?
Check the color (red, pink, brownish-red, and yellow), the vitreous to greasy luster, a Mohs hardness of 5–5.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Eudialyte?
Eudialyte has a Mohs hardness of 5–5.5. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Eudialyte and Chabazite?
Eudialyte (Mohs 5–5.5, vitreous to greasy luster) and Chabazite (Mohs 4–5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Eudialyte vs Chabazite comparison for a side-by-side table.
Is Eudialyte worth anything?
Entry-level Eudialyte specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Eudialyte?
Eudialyte is most often red, pink, brownish-red, and yellow. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
