Comparison · Minerals vs Silicate Minerals
Apophyllite vs Stilbite
Apophyllite and Stilbite are easy to confuse. Apophyllite is harder (Mohs 4.5–5) than Stilbite (Mohs 3.75), so Apophyllite will scratch Stilbite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Apophyllite and Stilbite
- Apophyllite is harder (Mohs 4.5–5) than Stilbite (Mohs 3.75), so Apophyllite will scratch Stilbite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Hold a thin edge to the light: Apophyllite is Transparent to translucent, Stilbite is transparent.
- They overlap in pink and yellow, but Apophyllite also comes in clear and green and Stilbite also comes in white and brown.
- Well-formed crystals give it away: Apophyllite is Tetragonal, Stilbite is monoclinic.
Apophyllite vs Stilbite properties
| Property | Apophyllite | Stilbite |
|---|---|---|
| Type | Minerals | Silicate Minerals |
| Mohs hardness | 4.5–5 | 3.75 |
| Luster | Vitreous, pearly on cleavage | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | transparent |
| Specific gravity | 2.3–2.4 | 2.2 |
| Crystal system | Tetragonal | monoclinic |
| Common colors | Colorless, White, Green, Pink, Pale yellow | White, Pink, Salmon, Yellow, Brown |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $5–$250+ |
Which is more valuable?
Stilbite is usually the more valuable of the two: a typical collector specimen runs about $40 against $20 for Apophyllite, and premium Stilbite can reach $250 or more.
About Apophyllite
Apophyllite is the common name for a small group of hydrated potassium calcium silicates, most often KCa4Si8O20(F,OH)·8H2O, crystallizing in the tetragonal system. It typically grows as glassy, pseudo-cubic or pyramidal crystals lining cavities in basaltic lava. The name comes from the Greek for 'to leaf away,' describing how the mineral flakes when heated, losing its water of crystallization.
About Stilbite
Stilbite is a calcium-rich zeolite mineral known for its distinctive sheaf-like or bowtie-shaped crystal aggregates. It commonly occurs as white to salmon-pink crystals lining cavities in basalt, often with other zeolites.
Apophyllite vs Stilbite FAQ
Is Apophyllite the same as Stilbite?
No. Apophyllite is a mineral while Stilbite is a silicate mineral. Apophyllite is harder (Mohs 4.5–5) than Stilbite (Mohs 3.75), so Apophyllite will scratch Stilbite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Apophyllite from Stilbite?
Apophyllite is harder (Mohs 4.5–5) than Stilbite (Mohs 3.75), so Apophyllite will scratch Stilbite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Hold a thin edge to the light: Apophyllite is Transparent to translucent, Stilbite is transparent. They overlap in pink and yellow, but Apophyllite also comes in clear and green and Stilbite also comes in white and brown.
Which is harder, Apophyllite or Stilbite?
Apophyllite is harder: Mohs 4.5–5 against Mohs 3.75 for Stilbite.
Which is more valuable, Apophyllite or Stilbite?
Stilbite is usually the more valuable of the two: a typical collector specimen runs about $40 against $20 for Apophyllite, and premium Stilbite can reach $250 or more.
