Fig. 7
From: On the formation of hörnesite in a Fatimid manuscript folio
a Photomicrograph of white crystals grown after 3 years on a mixture of orpiment, realgar and pararealgar applied on Whatman® filter paper and treated with a MgCO3 suspension. Visible illumination, original magnification ×10. b Integrated XRD pattern of the white crystals formed on the sample shown in a, with line patterns of arsenolite and hörnesite