Goethite

Goethite is a natural mineral pigment: ground goethite, the iron oxide-hydroxide α-FeO(OH) that also gives yellow ochre its color. This grade is an earthy brown with a yellow-olive tone. It is lightfast (8 of 8 in supplier tests) and lime-proof, for natural browns and earth tones in oil, egg tempera, watercolor, fresco and plaster.

Key facts

• Color: earthy brown with a yellow-olive tone
• Pigment type: Natural mineral pigment
• Colour Index: PY43 (C.I. 77492)
• Composition: iron(III) oxide-hydroxide, α-FeO(OH)
• Also known as: brown ochre
• 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

Mull the powder into linseed oil, egg yolk, gum arabic or acrylic medium with a palette knife or muller; it combines with any binder and any other pigment. Thin layers glaze, thicker ones cover. Keep it away from heat unless you want a change: heated, goethite loses its bound water and turns into red-brown iron oxide, so fired ceramics come out redder than the powder. For fresco, grind it in water and apply it to fresh lime plaster. Store it dry in a closed jar.

About goethite

Goethite was first described as a mineral in 1806 and named after the German poet Johann Wolfgang von Goethe. It is the main component of rust and of bog iron ore, which forms in marshes and meadows, and the coloring mineral of yellow ochres. It has been used as a pigment since ancient times, and heated to make a red pigment since the Paleolithic.

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

What is the difference between goethite and limonite?

Goethite is a single, defined mineral, α-FeO(OH). Limonite is a field name for mixtures of hydrated iron oxides such as goethite and lepidocrocite; our Limonite is a lighter yellow-brown.

Is goethite the same as yellow ochre?

Not quite. Yellow ochre is clay colored by goethite; this pigment is the iron mineral itself, here in a brown form.