Actinolite Value, Price, and Jewelry Information

Actinolite

Actinolite

Actinolite is a member of a series that contains varying amounts of iron and magnesium. Tremolite is the Mg end, and ferroactinolite the Fe end, with actinolite in the middle. Actinolites with more than 50% Fe are very rare. Catseye actinolite exists (S.G. 3.0, R.I. 1.63); when chatoyant material is cut, it exhibits a fine eye. Actinolite is easy to cleave and hard to cut and would make a poor jewelry stone. Actinolite is the chief constituent of nephrite (jade). Smaragdite is a chrome-rich tremolite from Tanzania.

Actinolite Value

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Actinolite Value via Gem Price Guide

Cut Weight Price
Cat’s Eye 1 carat /ct

Actinolite Information

Data Value
Name Actinolite
Varieties Smaragdite
Colors Pale to dark green, blackish green, black.
Crystallography Monoclinic; bladed crystals, usually elongated; fibrous, columnar aggregates. Also massive, granular, Often twinned.
Refractive Index 1.619-1.644
Luster Vitreous, sometimes dull.
Hardness 5.5
Fracture Uneven, Often fibrous nature
Specific Gravity Usually 3.05; Tanzania: 3.03-3.07; Max.: 3.44.
Birefringence 0.022-0.026.
Cleavage 2 directions good
Dispersion 0.009
Stone Sizes Actinolite is rarely facetable and usually in small fragments. Material from Chester, Vermont, could provide stones to about 10 carats. DG: 2.06 (greenish, step cut, Africa)
Luminescence None (due to presence of Fe).
Luminescence Present No
Transparency Translucent to transparent.
Absorption Spectrum Faint line at 5030.
Phenomena Chatoyancy.
Formula

Ca2(Mg, Fe)5Si8O22(OH)2

Pleochroism

Yellow to dark green. Material transparent to nearly opaque.
α: pale yellow/ yellowish-green.
β: pale yellow-green/green.
γ: pale green/ deep greenish blue.

Optics

α = 1.619-1.622; β = 1.632-1.634; γ = 1.642-1.644 (Tanzanian material). Biaxial (-); 2V = 78°. See chart for series member optics.

Optic Sign Biaxial -

Comments: Actinolite is a member of a series that contains varying amounts of iron and magnesium. Tremolite is the Mg end, and ferroactinolite the Fe end, with actinolite in the middle. Actinolites with more than 50% Fe are very rare. Catseye actinolite exists (S.G. 3.0, R.I. 1.63); when chatoyant material is cut, it exhibits a fine eye. Actinolite is easy to cleave and hard to cut and would make a poor jewelry stone. Actinolite is the chief constituent of nephrite (jade). Smaragdite is a chrome-rich tremolite from Tanzania.

Name: Greek aktis, meaning ray, due to the fibrous nature.

Optics:

α = 1.619-1.622;

β = 1.632-1.634;

γ = 1.642-1.644 (Tanzanian material).

Biaxial (-); 2V = 78°

Occurrence: Contact metamorphic limestones and dolomites; magnesium-rich limestones and ultrabasic rocks; regionally metamorphosed rocks.

Locality Pleochroic Colors α β γ Birefringence S.G. Comments
Fowler, New York red-violet 1.602 1.630 0.028 3.03 Hexagonite
Kenya bright green 1.602 1.613 1.628 0.026 2.99 Tremolite
1.607 1.618 1.632 0.025 3.01
Tanzania (Lelatema) yellow green/green 1.608 1.616 1.631 0.023 3.01 Tremolite
Tanzania emerald green 1.611 1.623 1.639 0.028 3.30 Tremolite + Cr
Tanzania (Merelani) yellow-green/emerald green 1.608 1.618 1.63 0.022 Smaragdite
Taiwan yellow-green/green tones, 1.607- 1.630- 0.023- 3.01 Tremolite
also brownish 1.609 1.633 0.024
1.615- 1.631- 0.014- 3.01 Catseye tremolite
1.619 1.633 0.016
Uganda yellow-green/green 1.619- 1.632- 1.642- 0.021- 3.04- Tremolite-Actinolite
1.622 1.634 1.644 0.024 3.07
green/brown 1.633 1.653 0.020 3.15 Actinolite
Chemical composition vs. optics and density of common hornblendes. Adapted from W.A. Deere, R.A. Howie, and J. Zussman, 1962, The Rock Forming Minerals, vol.2 (New York: Wiley), p.296.

Chemical composition vs. optics and density of common hornblendes.
Adapted from W.A. Deere, R.A. Howie, and J. Zussman, 1962, The Rock Forming Minerals, vol.2 (New York: Wiley), p.296.

Chester, Vermont.

Madagascar: small, dark green crystals. Many of these are clean and suitable for faceting.

Tanzania: transparent crystals. (See also nephrite.)