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Ocean Jasper is a distinctive variety of orbicular jasper, characterized by its striking spherical or 'orb' patterns, often resembling eyes or cellular structures. It exhibits a wide range of colors, including green, yellow, pink, red, white, grey, and brown, often in intricate combinations. The orbs are typically set within a contrasting matrix. It is a microcrystalline variety of quartz (chalcedony) and is known for its unique aesthetic appeal.
How to Identify
- Color
- Extremely variable, including shades of green, yellow, pink, red, white, cream, grey, and brown. Often multi-colored within a single specimen.
- Luster
- Vitreous to waxy, dull in unpolished specimens.
- Texture
- Smooth and dense when polished; rough to slightly granular in its natural state. Characterized by distinct orbicular patterns.
- Crystal Form
- Cryptocrystalline (microscopic crystals), forming botryoidal or mammillary masses within cavities, often with concentric banding.
- Cleavage
- None (due to its cryptocrystalline nature).
- Geological Environment
- Hydrothermal veins and amygdaloidal cavities within rhyolitic volcanic flows, typically found near coastal areas.
Key Facts
- Hardness: 6.5-7 on the Mohs scale
- Specific Gravity: 2.58-2.64
- Crystal System: Trigonal (cryptocrystalline aggregates)
- Color: Highly variable: green, yellow, pink, red, white, grey, brown, often multi-colored with orbicular patterns
- Luster: Vitreous to waxy
- Transparency: Opaque to translucent
- Fracture: Conchoidal to splintery
- Cleavage: None
- Composition: Silicon dioxide (SiO2) with various mineral inclusions
Quick Check
- Color: Multi-colored with orbicular patterns (green, yellow, pink, red, white, grey, brown)
- Luster: Vitreous to waxy
- Streak: White
Physical Characteristics
- Crystal Habit: Cryptocrystalline aggregates, forming botryoidal, mammillary, or nodular masses with concentric banding (orbicular structures).
- Cleavage Type: None
- Fracture Type: Conchoidal to splintery
- Tenacity: Brittle
- Luster Type: Vitreous to waxy
Formation
Ocean Jasper forms hydrothermally in silica-rich volcanic rocks, specifically rhyolite flows. Silica-rich fluids percolate through vesicles (gas bubbles) and fractures in the cooling lava. These fluids deposit concentric layers of chalcedony, quartz, and other minerals (such as iron oxides, chlorite, and other silicates) around a central nucleus or within existing cavities, creating the characteristic orbicular patterns. The presence of various trace minerals contributes to its diverse coloration.
Usage
Primarily used as an ornamental stone, for lapidary purposes (cabochons, spheres, carvings), and in jewelry. It is also popular among mineral collectors and for metaphysical practices.
Age Distribution
Formed during the Cenozoic Era, likely Miocene to Pliocene epochs, approximately 20-25 million years ago.
Where to Find
Marovato, Madagascar
The primary and original source of Ocean Jasper, located along the northwestern coast of Madagascar. It is found in remote, tide-dependent coastal areas, often requiring access by boat during low tide.
Kabamby, Madagascar
A second, distinct deposit also found in Madagascar, exhibiting slightly different color palettes and orbicular patterns compared to the Marovato material.
Finding Tips
Geological Context
Look for areas with rhyolitic volcanic activity, particularly where these rocks have undergone hydrothermal alteration and contain vesicles or fractures.
Coastal Access
The known deposits are coastal, often exposed only during low tides, suggesting exploration in similar geological settings along coastlines.
Orbicular Patterns
The most definitive identification feature is the presence of distinct, often multi-colored, spherical or 'orb' patterns within a chalcedony matrix.
Hardness Test
As a variety of quartz, it will scratch glass and steel (Mohs hardness 6.5-7).
Similar Rocks
Orbicular Granite
Orbicular Granitoid
Also known as: Orbicular Diorite, Orbicular Gabbro
Leopard Skin Jasper
Orbicular Jasper (variety)
Also known as: Mexican Leopard Skin Jasper
Kambaba Jasper
Stromatolitic Jasper
Also known as: Crocodile Jasper
Scientific Classification
- Mineral Class
- Silicate (Tectosilicate)
- Group
- Quartz Group (Chalcedony variety)
- Crystal System
- Trigonal (microcrystalline)
- Chemical Formula
- SiO2
- Composition
- Silicon dioxide, often with trace amounts of iron oxides, chlorite, and other silicates contributing to color and pattern.
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