Antofilita Bola o nódulo de Heřmanov
Antofilita is a mineral with formula (Mg,Fe²⁺)₇Si₈O₂₂(OH)₂ + KMg₃(AlSi₃O₁₀)(OH)₂, in the Anfíboles group. This specimen comes from Heřmanov, Žďár nad Sázavou, Vysočina, Región de Vysočina, República Checa and joined the Terrium collection in 2012.
Description
Well-formed radial aggregate of white, pearly anthophyllite laminae arranged in a crown, bordered by a thin green layer of chlorite encircling a dark, compact, lustrous phlogopite core. Specimen complete, symmetrical, undamaged, with notable sculptural aesthetics.
About Antofilita
The famous "Heřmanov Balls" (Heřmanovské koule) formed by a contact reaction: a silica-rich pegmatite vein intersected a silica-poor rock (the contact zone between granulites and ultramafic rocks). To balance that chemical contrast, a reaction zone—the ball—developed in which the phlogopite core was progressively transformed into anthophyllite towards the rims.
About the locality
Heřmanov is a small village in the Bohemian Highlands (Vysočina) known worldwide for these unique nodules. Declared a "Natural Monument" in 1978. As a protected site, collecting is restricted, so quality, complete specimens usually come from old collections.
Technical data
- Catalogue No.
- 0074
- Composition
- (Mg,Fe²⁺)₇Si₈O₂₂(OH)₂ + KMg₃(AlSi₃O₁₀)(OH)₂
- Name
- Antofilita
- Variety
- Bola o nódulo de Heřmanov
- Group
- Anfíboles
- Category
- Meritum Persé
- Matrix
- Flogopita
- Associations
- Clorito
- Mine
- Heřmanov
- District / Municipality
- Žďár nad Sázavou
- Province
- Vysočina
- Region
- Región de Vysočina
- Country
- República Checa
- Size (cm)
- 4.4 x 3 x 2.6
- Weight
- 35.7 g
- Acquired
- 2012
- Etymology
- From the Greek 'anthos' (flower) and 'phyllon' (leaf), referring to its platy habit and sometimes radial arrangement, as in this case.
- Quality
- Muy buena
- Value trend
- Estable
Related specimens
- Antofilita (Bola o nódulo de Heřmanov) — República Checa
- Discrasita — República Checa
- Granate (Hesonita (Grosularia)) — República Checa
- Hornblenda — Italia
- Metaorbernita — República Checa
- Ópalo (Hialita) — República Checa
- Tectita (Moldavita) — República Checa
- Torbernita — República Checa