Limonite

Limonite is a natural mineral pigment ground from limonite, a brown iron ore made of hydrated iron oxides such as goethite. It gives a soft yellow-brown, the same iron coloring that makes natural ochres yellow. It is lightfast (8 of 8 in supplier tests) and lime-proof, for warm earth tones in oil, egg tempera, watercolor, fresco and plaster.

Key facts

• Color: soft yellow-brown
• Pigment type: Natural mineral pigment
• Colour Index: PY43 (C.I. 77492)
• Composition: mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH₂O
• Also known as: brown iron ore, brown hematite, bog iron ore
• Opacity: semi-opaque
• Lightfastness: 8 of 8 on the Blue Wool Scale (supplier data)
• Chemical resistance: alkali 5/5, lime 5/5 (supplier data, 5 = best); stable in weak acids, dissolved by strong mineral acids
• Suitable for: oil, acrylic, egg tempera, watercolor, gouache, fresco (lime), lime and cement plaster, ceramics
• Packaging: 50 g jar · 1 kg bag

How to use

Like other yellow iron oxides it disperses easily: mull it into linseed oil, egg yolk, gum arabic or acrylic medium with a palette knife or muller. It is compatible with all other pigments. For fresco, grind it in water and apply it to fresh lime plaster. Limonite is sensitive to heat: above about 180 °C it begins to lose water, and at 270–300 °C it turns into red-brown iron oxide, so fired ceramics come out red. Store it dry and closed.

About limonite

Limonite is not a single mineral but a field name for mixtures of hydrated iron oxides. Its name comes from Greek and alludes to bog iron ore found in meadows and marshes. Its yellow form produced the yellow ochre for which Cyprus was famous, and roasting it gave red ochres, burnt siennas and umbers. Bog ore and limonite were also mined as a source of iron.

Safety

Natural iron ores can contain crystalline silica (quartz): avoid breathing the dust. Handle dry pigment with care: avoid breathing the dust and contact with eyes. Wear a dust mask (FFP2/N95) and gloves when working with the powder, work in a well-ventilated area and wipe up spills with a damp cloth. Do not eat, drink or smoke while working; wash your hands afterwards. Keep away from children and pets. For artistic and technical use only — not for cosmetics, food or tattoos.

FAQ

Is limonite a mineral?

Not strictly. It is a field term for a mixture of hydrated iron oxides such as goethite and lepidocrocite. Goethite, which we also sell, is the defined mineral.

What happens if limonite is heated?

It turns red: heating drives off water and converts it partly into hematite. Roasting limonite is how red ochres, burnt sienna and burnt umber get their color.