Prehnite with Epidote – Mali Ref568

🟢 Main description

This prehnite from Kayes, Mali shows a well-developed botryoidal growth with several pale green rounded masses. The surface displays a subtle radial, fibrous texture typical of compact aggregates of this species.

On the front face, a few dark spots can be seen within the prehnite; these correspond to small areas of included epidote formed during crystallisation.

The back of the specimen, by contrast, reveals epidote on a much larger scale. It forms a continuous dark base on which the prehnite has grown, giving the piece a compact, coherent structure. The contrast between the two faces clearly illustrates the relationship between the two minerals.

The specimen measures 30 mm across and 50 mm high, a size that allows for a clear view of both the textures and the distribution of prehnite and epidote.

🟢 Mineral information

- Chemical formula: Ca₂Al(AlSi₃O₁₀)(OH)₂

- Crystal system: Orthorhombic, most often found in compact or botryoidal aggregates

- Lustre: Vitreous, sometimes slightly silky.

- Hardness: Between 6 and 6.5 on the Mohs scale

- Density: Typically around 2.9–3.0 g/cm³

- Typical associations: Epidote is common in this locality, with possible quartz or calcite