Seraphinite
Seraphinite
Mg₅Al(Si₃Al)O₁₀(OH)₈ Properties
- Category
- Mineral
Seraphinite is a hydrated magnesium and aluminum silicate belonging to the chlorite group, characterized by a monoclinic crystal structure and very low hardness (2-2.5 on the Mohs scale). Its name derives from the legend of the Archangel Seraphim, inspired by the characteristic fibrous patterns that resemble angelic wings.
Seraphinite is a variety of chlorite, a phyllosilicate that forms predominantly in low-grade metamorphic environments, particularly in magnesium-rich rocks such as greenschists and altered serpentinites. Its monoclinic crystal structure reflects the ordered stacking of tetrahedral and octahedral layers, typical of minerals in the chlorite group. The chemical formula Mg₅Al(Si₃Al)O₁₀(OH)₈ highlights the alternation of magnesium and aluminum in octahedral sites, with hydroxyl groups (OH) providing the characteristic perfect cleavage.
The commercial name "seraphinite" was coined to describe specifically those chlorite specimens exhibiting particularly evident fibrous cleavage patterns, often sage green in color with silvery streaks reminiscent of seraphim wings. These specimens originate primarily from Siberia, particularly from the Lake Baikal region in Russia, where they occur in metamorphic deposits associated with ultramafic rocks. The very low hardness (2-2.5 Mohs) makes this mineral fragile and unsuitable for traditional jewelry, but it is appreciated by collectors for its aesthetic beauty and occasionally used in small decorative objects or cabochons.
Crystal system: monoclinic, space group C2/m. Unit cell parameters (typical for chlorite): a ≈ 5.3 Å, b ≈ 9.2 Å, c ≈ 14.3 Å, β ≈ 97°. Structural formula: (Mg,Fe)₅Al(Si₃Al)O₁₀(OH)₈, with compositional variability in the Mg:Fe ratio and in the distribution of Al between tetrahedral and octahedral sites. Hardness: 2-2.5 Mohs. Density: 2.75-2.85 g/cm³. Perfect cleavage along (001), generating characteristic thin and flexible laminae. Color: sage green, light green, sometimes with grayish-greenish tones. Luster: vitreous to pearly on cleavage surfaces. Transparency: translucent to opaque. Refractive index: nα ≈ 1.57-1.59, nγ ≈ 1.60-1.61; low birefringence (Δ ≈ 0.005-0.010). Weak pleochroism. IR spectroscopy: characteristic O-H stretching bands around 3500-3700 cm⁻¹; Si-O absorptions around 1000-1100 cm⁻¹. X-ray diffraction: marked basal reflections (00l), with periodicity that may indicate variable structural order. Mineral associations: serpentine, magnetite, talc, carbonates, epidote.
Mining localities
- Lago Baikal, Siberia, Russia
- Regione di Irkutsk, Russia
- Monti Sayan, Russia
- Depositi metamorfici dell'Asia centrale
Frequently Asked Questions
What is Seraphinite and where does its name come from?
Seraphinite is a hydrated magnesium and aluminum silicate belonging to the chlorite group, with the chemical formula Mg₅Al(Si₃Al)O₁₀(OH)₈. The name derives from the legend of the Archangel Seraphim, inspired by the mineral's fibrous and radiated characteristics that resemble an angel's wings. It is primarily extracted in Russia, in the Lake Baikal region, where it forms deposits of notable purity.
How do you identify Seraphinite and what are its physical characteristics?
Seraphinite is easily recognized by its pale green appearance with distinctive white radial striations that create a feather-wing effect, and its very low hardness of 2-2.5 on the Mohs scale. It has a monoclinic crystal structure, silky to vitreous luster, and is easily scratched with a knife. The color ranges from pale green to grey-green, with parallel fibrous bands that are its most distinctive feature.
What is the crystal structure of Seraphinite and how does it form?
Seraphinite has a monoclinic crystal structure characterized by layers of hydrated silicates with magnesium and aluminum inclusions, which confer the typical radial fibration. It forms in low to medium pressure metamorphic rocks, particularly in chloriteschists derived from altered ultramafic rocks. The layered structure and high water content in the chemical formula are responsible for its extreme friability and low hardness.
Where is Seraphinite found and what is its market price?
High-quality gem-grade Seraphinite is found primarily in Russia, particularly in the mountains of eastern Siberia near Lake Baikal, which is the world's main source. Prices vary greatly depending on quality, size, and purity: small rough specimens cost 5-15 euros per kilogram, while polished pieces of good quality can reach 20-50 euros per unit. Specimens with perfect wing striations and intense color are the most sought after in the collector market.
Entry generated with Claude API (Anthropic) on data extracted from Mindat, RRUFF and Wikipedia. Not yet reviewed by a human expert. Verify data against original sources before citing in formal work.
