mineral
Green Tourmaline (Verdelite) / Actinolite
Tourmaline group: Na(Mg,Fe,Li,Al,Mn)3Al6(BO3)3Si6O18(OH)4 / Actinolite: Ca2(Mg,Fe)5Si8O22(OH)2
AI-generated identification · may be incorrectHardness: 7-7.5 (Tourmaline) or 5.5-6 (Actinolite). Color: Deep olive-green to dark forest green with a metallic to vitreous sheen. Luster: Vitreous to pearly/silky. Crystal structure: Trigonal (Tourmaline) or Monoclinic (Actinolite), displaying prominent parallel striations and prismatic elongate form.
- Hardness
- 7-7
- Luster
- Vitreous to pearly/silky
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Physical properties
Hardness: 7-7.5 (Tourmaline) or 5.5-6 (Actinolite). Color: Deep olive-green to dark forest green with a metallic to vitreous sheen. Luster: Vitreous to pearly/silky. Crystal structure: Trigonal (Tourmaline) or Monoclinic (Actinolite), displaying prominent parallel striations and prismatic elongate form.
Formation & geological history
Formed in igneous pegmatites or metamorphic rocks such as schists and marbles under high pressure and regional/contact thermal conditions.
Uses & applications
Used in lapidary work, gemstone jewelry, crystal healing collections, and as decorative mineral specimens.
Geological facts
Tourmaline exhibits pyroelectric and piezoelectric properties, meaning it can generate an electrical charge when heated or subjected to mechanical pressure.
Field identification & locations
Identified by its prismatic vertical striations, dark green color, distinct pearly-to-vitreous luster, and high hardness. Commonly found in Brazil, Madagascar, Pakistan, and the USA.
