Map Jasper

Map Jasper is a trade name for an opaque variety of jasper whose markings call to mind a road or political map, with irregular cells of color bounded by darker dividing lines. Like all jasper it is microcrystalline quartz colored by iron oxides and clay impurities.

The stone is closely related to picture and landscape jaspers, differing mainly in the way its patterns read as bordered regions rather than scenery. It is valued by collectors and lapidaries for its one-of-a-kind cartographic designs.

Map Jasper forms when silica-rich groundwater percolates through volcanic ash, sediment, or fractured rock and slowly precipitates as a dense mass of microscopic quartz. Iron and manganese oxides carried in the fluids stain the silica and migrate along cracks.

The map-like pattern arises as contrasting mineral solutions deposit along a network of shrinkage cracks and bedding surfaces, outlining individual silica cells with darker borders. Compaction and continued silica cementation harden the mass into solid, take-a-polish jasper.

Identify Map Jasper by its opaque body and irregular bordered cells that resemble regions on a map, typically in earthy tans, browns, creams, and grays.

• Hardness: 6.5-7; scratches glass.
• Luster: waxy to dull raw, glassy when polished.
• Streak: white.
• Look-alikes: picture jasper shows scenic dune-and-sky imagery; brecciated jasper shows sharp angular fragments rather than soft bordered cells. The defining trait is the continuous outlining of color zones into map-like areas.

Map Jasper is primarily a decorative and lapidary stone, cut into cabochons, slabs, bookends, and tumbled pieces that showcase its picture-like patterns. Slab collectors prize specimens that resemble recognizable coastlines or terrain.

With a hardness near 7 it polishes well and resists scratching, making it suitable for pendants and statement jewelry. Metaphysically, jaspers are regarded as grounding stones, a traditional belief rather than a proven property.