One of a group of specimens illustrating the manufacture of Portland cement - a sample of chalk as quarried

Pharmaceutical jar of clear glass with a glass stopper, and with a brown paper label for chalk powder

Fossil heart sea-urchin, Micraster cortestudinarium, from the Upper Cretaceous Epoch of England

Framed painting in shades of red, green and purple in watercolour wash, pencil and black chalk, image abstracted from photograph of an Iresine plant, the second of seven related images in different media, produced in the development of the Lanzarote pattern: Scotland, Galashiels, by Bernat Klein, 1979

Framed painting in shades of red, green and purple in watercolour wash, pencil and black chalk, image abstracted from photograph of an Iresine plant, the third of seven related images in different media, produced in the development of the Lanzarote pattern: Scotland, Galashiels, by Bernat Klein, 1979

Framed painting in shades of red, pink, green and purple in oil paint and black chalk or charcoal, image abstracted from photograph of an Iresine plant, the fourth of seven related images in different media, produced in the development of the Lanzarote pattern: Scotland, Galashiels, by Bernat Klein, 1979

Framed painting in shades of blue, red, pink, purple and green in watercolour wash, pencil and black chalk, image abstracted from photograph of an Iresine plant, the fifth of seven related images in different media, produced in the development of the Lanzarote pattern: Scotland, Galashiels, by Bernat Klein, 1979