Yellow Jasper

Yellow jasper is an opaque, golden- to mustard-yellow variety of jasper, the impure microcrystalline form of quartz (silicon dioxide). Its warm color comes from iron oxide impurities, chiefly limonite and goethite, distributed through the fine-grained quartz.

Jasper differs from translucent chalcedony and agate in being fully opaque due to a high content of foreign mineral matter, sometimes 20 percent or more. Yellow jasper may be a uniform solid color or show mottling, veining, and banding.

Durable, takes an excellent polish, and inexpensive, yellow jasper is a popular material for beads, cabochons, tumbled stones, and ornamental carvings.

Yellow jasper forms when silica-rich fluids cement and replace fine sediment, volcanic ash, or fractured rock, with iron-oxide impurities incorporated during deposition. The silica precipitates as microcrystalline quartz, binding the impurities into a hard, compact mass.

It commonly occurs as nodules, seams, and replacement bodies in sedimentary and volcanic settings. The yellow to ochre color reflects oxidized (ferric) iron; related jaspers in red, brown, and green reflect different iron states and impurities.

Jasper is found worldwide; notable yellow material comes from places such as India, Australia, Brazil, the United States, and South Africa.

Look for an opaque, solid yellow to golden or mustard stone, often with mottling or veining, taking a smooth high polish. Hardness is 6.5-7, luster waxy to dull, fracture conchoidal, no cleavage. Streak is white to pale yellow.

Its complete opacity separates jasper from translucent yellow chalcedony, citrine, and agate. The hardness of about 7 distinguishes it from softer yellow stones like calcite or serpentine.

Distinguish yellow jasper from yellow marble (softer, fizzes in acid) and from man-made glass (may show bubbles). Within jasper, color and pattern separate it from red, brown, and mookaite varieties.

Yellow jasper is used mainly as an ornamental and lapidary stone. Its toughness and even color make it ideal for beads, cabochons, tumbled stones, pendants, and small carvings, as well as inlay and decorative objects.

Affordable and durable, it is a staple of fashion jewelry and crafts, and it has been used since antiquity for seals and ornaments.

Metaphysically, yellow jasper is associated with energy, confidence, protection during travel, and the solar plexus chakra, said to promote vitality and positivity. These are spiritual beliefs rather than scientifically established properties.