Pyrolusite

Pyrolusite is a natural black pigment ground from the mineral pyrolusite, manganese dioxide. It gives a dense gray-black with good tinting strength, is fully lightfast and resists alkalis and lime. In oil it speeds drying, which suits underpainting and dark mixtures; it also works in acrylic, egg tempera, watercolor and gouache.

Key facts

• Color: gray-black (black with a gray tint)
• Pigment type: Natural mineral pigment
• Colour Index: PBk14 (C.I. 77728)
• Composition: manganese dioxide, MnO₂
• Also known as: black oxide of manganese
• Opacity: semi-opaque
• Lightfastness: 8 of 8 on the Blue Wool Scale (supplier data)
• Chemical resistance: alkali 5/5, lime 5/5, acid 5/5 (supplier data, 5 = best); hot hydrochloric acid dissolves it and releases chlorine
• Suitable for: oil, acrylic, egg tempera, watercolor, gouache
• Packaging: 50 g jar · 1 kg bag

How to use

Mull the powder into linseed oil, acrylic medium, egg yolk or gum arabic. Crystalline pyrolusite is hard (Mohs 6 to 6.5), so mix the ready powder with a muller rather than regrinding it in a porcelain mortar (supplier advice). Manganese dioxide accelerates the drying of oils and is used to make driers, so oil paint containing it dries quickly. Its density is close to that of other pigments, so it does not float or separate in mixtures (supplier).

About pyrolusite

The name comes from the Greek words for fire and washing, because glassmakers used pyrolusite to remove unwanted tints from glass. It is a main ore of manganese and also colors glass, pottery and bricks violet, amber or black. Manganese dioxide was used in some early European cave paintings, and blocks of pyrolusite are often found at Neanderthal sites.

Safety

Contains manganese dioxide: harmful if swallowed or inhaled. 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 pyrolusite toxic?

It is harmful if swallowed or inhaled. Avoid raising dust, wear a mask and gloves, and wash your hands after work.

Does pyrolusite dry quickly in oil?

Yes. Manganese dioxide accelerates the drying of oils, so oil colors containing it dry faster than usual.

Pyrolusite or shungite black?

Both are natural mineral blacks. Pyrolusite, a manganese oxide, is a grayer black that speeds drying in oil; shungite black is carbon-rich, deeper and slightly bluish, and dries slowly in oil.