Public domain photos

The image shows a piece of rock sitting on top of a table next to a ruler, with a scale and color chart beside it. The scale has numbers and text on it, and there is a paper with text at the bottom of the image.

The image shows a piece of rock sitting on top of a table next to a ruler, with a scale and color chart beside it. The scale has numbers and text on it, and there is a paper with text at the bottom of the image.Open in library