Girolita Verde
Girolita is a mineral with formula Ca₁₆Na₈Al₄₈Si₉₆O₃₈₄·92H₂O, in the Silicatos (Filosilicatos) group. This specimen comes from Malad Quarry, Mumbai Suburban District, Konkan, Maharashtra, India and joined the Terrium collection in 2024.
Description
Green spheroidal aggregates of gyrolite on a white crystalline matrix with quartz, with dark zones in the matrix that enhance the contrast. The arrangement forms a broad, aesthetic cavity, with well-defined, lustrous spheroids, which increases the visual appeal of the specimen.
History of this specimen
This piece belonged to the collection of Carles Manresa with the number 106—numbering that I have made to match mine—and is the specimen photographed and documented on Mindat (Photo ID 326634, Specimen MinID 2KP-L66). The provenance recorded on Mindat is incorrect; the real locality is Malad Quarry, Mumbai Suburban District, Maharashtra. A historic specimen with documented traceability. It was also the first piece with which I used an electronic calliper to measure it.
About Girolita
Gyrolite is a hydrated calcium–sodium phyllosilicate that typically forms in cavities of basalts, where it develops characteristic spheroidal aggregates. Its name derives from its globular habit ("gyros" in Greek means "round").
About the locality
Its classic Indian locality is well known for producing high-quality gyrolite, but specimens with well-defined spheroids associated with fine quartz, like this one, are scarce and sought after.
Technical data
- Catalogue No.
- 0106
- Composition
- Ca₁₆Na₈Al₄₈Si₉₆O₃₈₄·92H₂O
- Name
- Girolita
- Variety
- Verde
- Group
- Silicatos (Filosilicatos)
- Category
- Cavella
- Matrix
- Cuarzo
- Mine
- Malad Quarry
- District / Municipality
- Mumbai Suburban District
- Province
- Konkan
- Region
- Maharashtra
- Country
- India
- Size (cm)
- 52 x 42 x 35
- Weight
- 86 g
- Acquired
- 2024
- Ex-collection
- Carles Manresa
- Etymology
- From the Greek "gyros" (round) and "lithos" (stone), in reference to its characteristic spheroidal aggregates.
- Quality
- Buena
- Value trend
- Estable