Malachite pigment of spherical particle form

Abstract

Malachite of spherulitic particle form is generally thought to be synthetic in origin. However, it could be mineral malachite formed by natural precipitation from flowing water. Agricola described a source of this type in Neusohl (Banská Bystrica, Slovakia) in 1546. This hypothesis was considered by evaluation of historical documentary sources on green pigment production in the Neusohl region, and the geological literature. Precipitation experiments imitating the natural conditions produced malachite of spherulitic form, and several wall paintings in Neusohl were found to contain spherulitic malachite. Evidence that these, and examples from Italian paintings, could be from a naturally precipitated source is presented.