Rock Identifier
Jasper, possibly Brecciated Jasper or Ocean Jasper due to patterns and color (Silicon Dioxide (SiO2), a variety of Chalcedony) — Sedimentary Rock
Sedimentary Rock

Jasper, possibly Brecciated Jasper or Ocean Jasper due to patterns and color

Silicon Dioxide (SiO2), a variety of Chalcedony

Hardness: 6.5-7 on the Mohs scale. Color: Highly variable, often red, brown, yellow, green, or patterns combining these with white/grey. The specimen shows prominent reds, browns, and yellows with some grey/white. Luster: Dull to vitreous, often waxy.…

Hardness
6
Luster
Dull to vitreous, often waxy
Identified More sedimentary rock

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Physical properties

Hardness: 6.5-7 on the Mohs scale. Color: Highly variable, often red, brown, yellow, green, or patterns combining these with white/grey. The specimen shows prominent reds, browns, and yellows with some grey/white. Luster: Dull to vitreous, often waxy. Crystal Structure: Trigonal (microcrystalline quartz), not visible to the naked eye. Cleavage: None. Specific Gravity: 2.58-2.91.

Formation & geological history

Jasper is a cryptocrystalline variety of quartz, meaning its crystals are too fine to be seen without high magnification. It forms when silica-rich waters, often hydrothermal, precipitate colloidal silica, which then dehydrates and compacts. The distinct patterns and colors are due to impurities (such as iron oxides for reds and yellows) and how the silica precipitated and solidified. Brecciated jasper refers to fractured jasper cemented back together, which the irregular patterns in the specimen might suggest. Ocean Jasper is specifically found in Madagascar and is known for its orbicular patterns, though this specimen's patterns are more irregular and mossy/dendritic. Geological Age: Varies widely, found in deposits from various geological eras.

Uses & applications

Commonly used as an ornamental stone, for carving, and in jewelry (cabochons, beads). Its diverse patterns and colors make it popular for decorative items and lapidary work. It is also collected by mineral enthusiasts.

Geological facts

Jasper has been used for millennia for adornment and tools. Known as the 'supreme nurturer,' it is believed to sustain and support through times of stress, and brings tranquility and wholeness. The name jasper means 'spotted stone' and comes from the Old French 'jaspre,' and Latin 'iaspis.'

Field identification & locations

To identify in the field, look for its characteristic opaque appearance and often vibrant, earthy colors (red, brown, yellow, green) with distinct patterns. It will scratch glass but cannot be easily scratched by a knife due to its hardness (6.5-7). It often occurs in nodules or as fillings in veins in various rock types. Commonly found globally, with specific varieties like Ocean Jasper found in Madagascar, and other attractive jaspers found in areas like Oregon (USA), India, Russia, and Australia.