Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Rhodonite is a manganese inosilicate mineral, part of the pyroxenoid group, characterized by its distinctive pink to reddish-pink color, often with black dendritic or veined inclusions of manganese oxides (typically rhodochrosite or franklinite). The name 'rhodonite' comes from the Greek word 'rhodon', meaning 'rose', referring to its characteristic color. Tumbled rhodonite refers to pieces of the mineral that have been polished in a rock tumbler to achieve a smooth, lustrous surface, enhancing its aesthetic appeal for use in jewelry or as decorative stones.
How to Identify
- Color
- Pink to rose-red, often with black manganese oxide veins or dendrites. Can also be brownish-red.
- Luster
- Vitreous (glassy) to pearly on cleavage surfaces.
- Texture
- Typically massive, granular, or compact. Tumbled specimens will have a smooth, polished feel.
- Crystal Form
- Usually massive, granular, or compact. Well-formed crystals are rare and typically tabular or prismatic, belonging to the triclinic system.
- Cleavage
- Perfect in two directions at nearly right angles (87° and 93°), which can be observed in fractured or unpolished specimens.
- Geological Environment
- Metamorphic manganese deposits, skarns, hydrothermal veins, and occasionally as a primary mineral in igneous rocks.
Key Facts
- Hardness: 5.5-6.5 (Mohs scale)
- Specific Gravity: 3.4-3.7 g/cm³
- Crystal System: Triclinic
- Color: Pink, rose-red, brownish-red, often with black manganese oxide inclusions
- Luster: Vitreous to pearly
- Transparency: Translucent to opaque
- Fracture: Uneven to conchoidal
- Cleavage: Perfect in two directions at 87° and 93°
- Composition: Manganese inosilicate, MnSiO₃
Quick Check
- Color: Pink to rose-red, often with black veins
- Luster: Vitreous to pearly
- Streak: White
Physical Characteristics
- Crystal Habit: Typically massive, granular, or compact. Rarely as tabular or prismatic crystals.
- Cleavage Type: Perfect on {110} and {1-10} at nearly 90 degrees.
- Fracture Type: Uneven to conchoidal.
- Tenacity: Brittle.
- Luster Type: Vitreous to pearly on cleavage surfaces.
Formation
Rhodonite typically forms in metamorphic environments, particularly in manganese-rich sedimentary rocks that have undergone regional or contact metamorphism. It can also occur in hydrothermal veins and as a primary mineral in some igneous rocks. The presence of manganese and silica under specific pressure and temperature conditions is crucial for its formation.
Usage
Rhodonite is primarily used as an ornamental stone, particularly for cabochons, beads, carvings, and small sculptures. Its attractive pink to red color and often striking black manganese oxide inclusions make it popular in jewelry and decorative items. It is also collected by mineral enthusiasts.
Age Distribution
Rhodonite forms in various geological settings, often associated with manganese deposits, which can range in age from Precambrian to Cenozoic, depending on the specific deposit.
Where to Find
Franklin, New Jersey, USA
Known for producing some of the finest rhodonite specimens, often associated with zinc and manganese ore deposits.
Broken Hill, New South Wales, Australia
A significant source of rhodonite, often found in large masses suitable for carving and ornamental use.
Sweden
Historically important localities, particularly in the Värmland region.
Russia (Ural Mountains)
Produces high-quality rhodonite, sometimes referred to as 'Orletz'.
Brazil
Various occurrences, often associated with other manganese minerals.
Peru
Known for some rhodonite deposits.
Japan
Localities producing rhodonite, often in metamorphic settings.
Finding Tips
Geological Context
Look for rhodonite in areas known for manganese deposits, especially those that have undergone metamorphism. It is often found alongside other manganese minerals.
Associated Minerals
Rhodonite can be found with rhodochrosite, bustamite, spessartine garnet, franklinite, zincite, and various manganese oxides.
Color and Inclusions
Its distinctive pink to rose-red color, often with black manganese oxide patterns, is a key identifier. Be aware that some rhodonite can be more brownish-red.
Hardness Test
With a Mohs hardness of 5.5-6.5, rhodonite can scratch glass but can be scratched by quartz. This helps differentiate it from softer or harder pink minerals.
Cleavage Observation
If examining unpolished specimens, look for the characteristic perfect cleavage in two directions at nearly 90 degrees.
Similar Rocks
Rhodochrosite
Rhodochrosite
Also known as: Manganese Spar
Thulite
Thulite (variety of Zoisite)
Also known as: Pink Zoisite
Pink Tourmaline
Elbaite (variety of Tourmaline)
Also known as: Rubellite
Scientific Classification
- Mineral Class
- Silicates
- Group
- Pyroxenoid Group
- Crystal System
- Triclinic
- Chemical Formula
- MnSiO₃
- Composition
- Manganese (Mn), Silicon (Si), Oxygen (O). Can contain minor amounts of iron (Fe), magnesium (Mg), and calcium (Ca) substituting for manganese.
Explore Rhodonite
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.