Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Red Jasper is an opaque, microcrystalline variety of quartz (chalcedony) characterized by its vibrant red to reddish-brown coloration. This color is due to the presence of iron oxides, predominantly hematite, finely dispersed within the silica matrix. It typically exhibits a dull to vitreous luster and a conchoidal fracture. Its dense, fine-grained structure makes it durable and suitable for polishing.
How to Identify
- Color
- Opaque red, reddish-brown, brick-red, or sometimes mottled with other colors.
- Luster
- Dull to vitreous, often waxy on fractured surfaces.
- Texture
- Fine-grained, dense, and smooth when polished. Can feel slightly gritty on unpolished surfaces.
- Crystal Form
- Massive, cryptocrystalline aggregates; individual crystals are microscopic and not visible to the naked eye.
- Cleavage
- None, exhibits conchoidal fracture.
- Geological Environment
- Hydrothermal veins, volcanic rocks, sedimentary beds (especially banded iron formations), and as secondary infillings in various rock types. Often found in areas with past or present volcanic activity or significant hydrothermal alteration.
Key Facts
- Hardness: 6.5-7 on the Mohs scale
- Specific Gravity: 2.58-2.64 g/cm³
- Crystal System: Trigonal (for quartz component)
- Color: Red, reddish-brown, brick-red
- Luster: Dull to vitreous, waxy on fracture
- Transparency: Opaque
- Fracture: Conchoidal
- Cleavage: None
- Composition: Silicon dioxide (SiO2) with iron oxide (hematite, Fe2O3) inclusions
Quick Check
- Color: Opaque red to reddish-brown
- Luster: Dull to waxy
- Streak: Reddish-brown (due to hematite)
Physical Characteristics
- Crystal Habit: Massive, cryptocrystalline aggregates, nodular, botryoidal, or as vein fillings.
- Cleavage Type: Absent
- Fracture Type: Conchoidal to splintery
- Tenacity: Brittle
- Luster Type: Dull to vitreous, waxy
Formation
Red Jasper forms primarily through the precipitation of silica-rich fluids, often in association with volcanic activity or hydrothermal alteration. The characteristic red color is imparted by finely disseminated hematite (Fe2O3) inclusions, which are typically introduced during or after the silica precipitation. It can form as primary deposits in veins, nodules, or as replacement material in sedimentary rocks. It is also commonly found as a component of banded iron formations (BIFs) or as a secondary mineral in altered igneous rocks.
Usage
Red Jasper is widely used as an ornamental stone, for cabochons, beads, carvings, and polished specimens. Historically, it has been used for seals, intaglios, and other decorative objects. Due to its hardness and durability, it is also used in some lapidary applications.
Age Distribution
Found in geological formations ranging from Precambrian to Cenozoic, depending on the specific deposit.
Where to Find
India
Known for high-quality Red Jasper, particularly from the Deccan Traps region.
Brazil
Significant deposits found in various states, often associated with volcanic and sedimentary formations.
United States
Found in numerous states including Oregon, Idaho, California, and Arizona, often in association with volcanic or hydrothermal deposits.
Madagascar
Produces a variety of jaspers, including red varieties.
Egypt
Historically a source of jasper, used in ancient artifacts.
Finding Tips
Look for Associated Minerals
Red Jasper often occurs with other silica minerals, iron oxides, and sometimes in association with volcanic rocks like basalt or rhyolite, or in sedimentary chert beds.
Check Riverbeds and Gravel Pits
Due to its hardness and resistance to weathering, Red Jasper can be found as pebbles and cobbles in alluvial deposits.
Examine Outcrops in Volcanic Regions
Areas with past volcanic activity or hydrothermal alteration are prime locations for finding jasper veins or nodules.
Observe Color and Opacity
The distinctive opaque red color is the primary identifier. Translucent red chalcedony would be carnelian.
Similar Rocks
Carnelian
Chalcedony (microcrystalline quartz) with iron oxide impurities
Also known as: Cornelian
Sard
Chalcedony (microcrystalline quartz) with iron oxide impurities
Also known as: Sardonyx (when banded with onyx)
Chert
Microcrystalline quartz
Also known as: Flint (a variety of chert)
Scientific Classification
- Mineral Class
- Silicate (Tectosilicate)
- Group
- Quartz Group (Chalcedony variety)
- Crystal System
- Trigonal (for the constituent quartz microcrystals)
- Chemical Formula
- SiO2 (with Fe2O3 inclusions)
- Composition
- Primarily silicon dioxide, with varying amounts of iron oxides (hematite) responsible for the red coloration.
Explore Red Jasper
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.