Natural Rough Opal Madagascar Mineral Specimen 20-40mm Raw Precious Stone

Natural Rough Opal Madagascar Mineral Specimen 20-40mm Raw Precious Stone

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Genuine Natural Rough Opal – Madagascar Mineral Specimen

This listing is for a genuine Natural Rough Opal from Madagascar, sized approximately 20–40mm. The photograph shown represents an example of the actual specimen you will receive. Each piece is carefully selected for its natural character, colour variation, and collector appeal in its raw, unpolished state.

Your specimen includes a Certificate of Authenticity lifetime guarantee generic card, confirming it is a genuine natural mineral. Please refer to the photographs for full sizing and scale details.

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Mineral Species & Scientific Classification

Opal is a mineraloid composed of hydrated amorphous silica, with the chemical formula SiO₂·nH₂O. Unlike crystalline quartz, opal does not have a defined crystal structure, which is why it is classified as a mineraloid rather than a true mineral.

Key characteristics:

• Mineral Type: Opal (Hydrated Silica)

• Chemical Formula: SiO₂·nH₂O

• Crystal System: Amorphous (no crystalline structure)

• Hardness: Approximately 5.5–6.5 on the Mohs scale

• Lustre: Vitreous to waxy

• Transparency: Opaque to translucent

Opal forms when silica-rich solutions deposit microscopic silica spheres in cavities and fractures within host rock. The arrangement of these spheres can influence the stone’s appearance, including potential internal colour effects.

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Geological Formation & Madagascar Origin

Madagascar is internationally recognised for producing a wide variety of opal types, including common opal and material with internal colour flashes. Opal typically forms in sedimentary or volcanic environments where silica-rich water slowly fills voids in rock.

Over time, the gradual evaporation of water leaves behind deposits of hydrated silica. Depending on geological conditions, this process can create:

• Opaque white or cream opal

• Translucent opal with milky appearance

• Material displaying subtle internal colour

• Matrix-hosted opal within surrounding rock

Madagascar’s diverse geology contributes to the variation in texture and colour seen in these specimens.

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Rough Natural Form & Surface Features

This specimen is presented in natural rough form, preserving the authentic texture created during formation and extraction. Rough opal may display:

• Irregular natural surfaces

• Host rock matrix attached

• Colour zoning or layered structure

• Subtle internal light reflection

• Earthy exterior with brighter interior areas

Rough opal is especially valued by collectors and lapidary enthusiasts who appreciate natural, unpolished material.

Each piece is untreated and remains in its natural state.

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Size & Collector Appeal (20–40mm)

At approximately 20–40mm, this opal specimen offers a versatile size suitable for:

• Mineral and gemstone collections

• Lapidary and cutting projects (subject to suitability)

• Geological study

• Display in specimen trays

• Unique gifts for stone and mineral enthusiasts

The size range allows visible natural features while remaining manageable for display or crafting purposes.

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Optical Characteristics & Traditional Associations

Opal is admired for its unique internal structure and natural variation. Some pieces may show subtle internal colour effects depending on lighting and silica structure, while others present soft, uniform tones.

In various traditions, opal has been traditionally associated with inspiration and symbolic creativity. This listing presents the specimen strictly as a natural geological collectible, without any medical or outcome-based claims.

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Authenticity & Product Details

• Genuine Natural Rough Opal

• Origin: Madagascar

• Size Range: Approximately 20–40mm

• Hydrated amorphous silica mineraloid

• Natural, untreated specimen

• Carefully selected collector piece

• Includes Certificate of Authenticity lifetime guarantee generic card

• Photo shows an example of the actual specimen you will receive

A distinctive Madagascan rough opal specimen, showcasing the natural beauty and geological uniqueness of hydrated silica in its raw, collectible form.