Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Bloodstone, also known as heliotrope, is a distinctive variety of chalcedony (a cryptocrystalline form of quartz) characterized by its dark green body color with prominent red, blood-like spots or streaks. The green matrix is typically opaque to translucent, and the red inclusions are due to iron oxide minerals, predominantly hematite. It is a durable and relatively common gemstone.
How to Identify
- Color
- Dark green body with distinct red, blood-like spots or streaks. The green can range from dark forest green to a slightly lighter, mossy green.
- Luster
- Waxy to dull, sometimes vitreous when polished.
- Texture
- Smooth when polished; cryptocrystalline structure means individual crystals are not visible to the naked eye.
- Crystal Form
- Massive, cryptocrystalline aggregates. Does not form macroscopic crystals.
- Cleavage
- None, due to its cryptocrystalline nature.
- Geological Environment
- Found in alluvial deposits, as pebbles in riverbeds, and within veins or cavities in igneous or metamorphic rocks, particularly those that have undergone hydrothermal alteration.
Key Facts
- Hardness: 6.5-7 on Mohs scale
- Specific Gravity: 2.58-2.64
- Crystal System: Trigonal (cryptocrystalline)
- Color: Dark green with red spots
- Luster: Waxy to dull
- Transparency: Opaque to translucent
- Fracture: Conchoidal to uneven
- Cleavage: None
- Composition: Silicon Dioxide (SiO2) with iron oxide (hematite) and chlorite/hornblende inclusions
Quick Check
- Color: Dark green with red spots/streaks
- Luster: Waxy to dull
- Streak: White
Physical Characteristics
- Crystal Habit: Massive, cryptocrystalline aggregates; typically found as nodules, pebbles, or vein fillings.
- Cleavage Type: None, due to its microcrystalline structure.
- Fracture Type: Conchoidal to uneven, typical of cryptocrystalline quartz.
- Tenacity: Brittle
- Luster Type: Waxy to dull, sometimes vitreous on freshly broken surfaces.
Formation
Bloodstone is a cryptocrystalline variety of quartz (chalcedony) that forms from silica-rich solutions precipitating in cavities or fractures within existing rocks. The characteristic red spots are due to inclusions of iron oxides, primarily hematite (Fe2O3). The green color is attributed to chlorite or hornblende inclusions. It typically forms at relatively low temperatures and pressures.
Usage
Historically used as a gemstone, for carving, and in signet rings. In ancient times, it was believed to have magical and healing properties. Today, it is primarily used in jewelry (cabochons, beads), ornamental carvings, and as a collector's mineral.
Age Distribution
Formed throughout geological history, often associated with volcanic activity or hydrothermal alteration.
Where to Find
India
Major source, particularly from the Deccan Traps region.
Australia
Significant deposits are found in various regions.
Brazil
Known for producing good quality bloodstone.
China
Various occurrences throughout the country.
United States
Found in areas like California and Oregon.
Germany
Historical sources, particularly in the Idar-Oberstein region.
Finding Tips
Look in Alluvial Deposits
Bloodstone is often found as water-worn pebbles in riverbeds and stream gravels, especially in areas with historical volcanic activity.
Examine Rock Outcrops
Search for veins or nodules within igneous (e.g., basalt, andesite) or metamorphic rocks that show signs of hydrothermal alteration.
Check for Green and Red
The distinctive dark green color with red spots is the primary identifier. Look for these characteristics in weathered rock fragments.
Hardness Test
As a variety of quartz, bloodstone will scratch glass and steel (Mohs hardness 6.5-7). This helps differentiate it from softer green minerals.
Similar Rocks
Jasper
Silicon Dioxide (SiO2) with various impurities
Also known as: Various types of Jasper
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
Also known as: Aventurine Quartz
Epidote
Ca2(Al,Fe)3(SiO4)3(OH)
Also known as: Pistacite
Scientific Classification
- Mineral Class
- Silicate (Tectosilicate)
- Group
- Quartz Group (Chalcedony variety)
- Crystal System
- Trigonal (microcrystalline)
- Chemical Formula
- SiO2 (with Fe2O3 and other inclusions)
- Composition
- Primarily silicon dioxide, with iron oxides (hematite) responsible for the red coloration and chlorite or hornblende for the green matrix.
Explore Bloodstone
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.