Ferro-actinolita
Ferro-actinolita is a mineral with formula Ca₂Fe₅Si₈O₂₂(OH)₂, in the Silicato [Inosilicato (Grupo anfíbol)] group. This specimen comes from Shigar Mines, Shigar Valley, Shigar District, Gilgit-Baltistán, Pakistán.
Description
Very slender prismatic crystal, black, with pronounced longitudinal striation and vitreous–silky lustre; near-hexagonal cross-section visible at the ends, partially terminated and matrix-free.
About Ferro-actinolita
An iron-rich calcic amphibole, the iron end-member of the tremolite–actinolite series; it crystallises in the monoclinic system and commonly occurs in acicular or prismatic aggregates with perfect cleavage.
About the locality
The Shigar Valley, in Gilgit-Baltistan, hosts numerous pegmatites and metamorphic rocks that produce well-formed prismatic crystals (beryl, tourmaline, amphiboles), with highly aesthetic specimens for collectors.
Technical data
- Catalogue No.
- 0117
- Composition
- Ca₂Fe₅Si₈O₂₂(OH)₂
- Name
- Ferro-actinolita
- Group
- Silicato [Inosilicato (Grupo anfíbol)]
- Category
- Estélites
- Mine
- Shigar Mines
- District / Municipality
- Shigar Valley
- Province
- Shigar District
- Region
- Gilgit-Baltistán
- Country
- Pakistán
- Size (cm)
- 7 x 0.8 x 0.5
- Weight
- 5.9 g
- Etymology
- From the Greek "aktis/aktinos" ("ray"), referring to its fibrous habit; the prefix "ferro-" refers to its iron-rich composition.
- Quality
- Muy buena
- Value trend
- Estable
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