Comparison · Minerals
Actinolite vs Diopside
Actinolite and Diopside are easy to confuse because both are minerals. Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Actinolite and Diopside
- Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Actinolite is Translucent to opaque, Diopside is Transparent to translucent.
- They overlap in green, gray, and black, but Diopside also comes in white, blue, purple, and multicolored.
Actinolite vs Diopside properties
| Property | Actinolite | Diopside |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5–6 | 5.5–6.5 |
| Luster | Vitreous to silky | Vitreous |
| Streak | White | White |
| Transparency | Translucent to opaque | Transparent to translucent |
| Specific gravity | 3.0–3.2 | 3.2–3.3 |
| Crystal system | Monoclinic | Monoclinic |
| Common colors | Green, Dark green, Grayish green, Black | Light to dark green, White, Gray, Blue-violet (violane), Black (chromian varieties) |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Actinolite and Diopside trade in a similar range, around $20.
About Actinolite
Actinolite is a calcium-magnesium-iron amphibole with the formula Ca2(Mg,Fe)5Si8O22(OH)2, part of the tremolite-actinolite-ferro-actinolite solid solution series. Its green color comes directly from iron substituting for magnesium within the crystal structure, and it typically grows as elongated, bladed to fibrous crystals. The mineral is best known to rockhounds as a key component of nephrite jade.
About Diopside
Diopside is a calcium magnesium silicate pyroxene mineral, CaMgSi2O6, common in metamorphosed limestones and mafic to ultramafic igneous rocks. It typically forms stubby prismatic crystals with a nearly square cross-section, a hallmark of the pyroxene group's characteristic cleavage angles. Diopside's color ranges from colorless to deep green depending on iron and chromium content, and chromium-rich varieties are prized as gem material.
Actinolite vs Diopside FAQ
Is Actinolite the same as Diopside?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Actinolite from Diopside?
Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Actinolite is Translucent to opaque, Diopside is Transparent to translucent. They overlap in green, gray, and black, but Diopside also comes in white, blue, purple, and multicolored.
Which is harder, Actinolite or Diopside?
Diopside is harder: Mohs 5.5–6.5 against Mohs 5–6 for Actinolite.
Which is more valuable, Actinolite or Diopside?
Typical specimens of Actinolite and Diopside trade in a similar range, around $20.
