Awhile back I wrote a post, Mysteries of Kourion, about an unusual object from Kaloriziki Kourion (an archaeological site on Cyprus), which rattles when moved. Last week I got to revisit the question of what exactly is making that noise, as this object along with a number of objects from the Egyptian section were taken on an excursion for X-radiography and CT scanning. Although this object was not CT scanned during our trip, it was X-rayed using a system similar to what we will have as part of the soon to begin renovations of the conservation labs here at the museum. You can learn about one of the Egyptian artifacts and the CT scanning from the Artifact Lab Blog post, Looking Inside our Falcon Mummy.
X-rays can be used not only to reveal internal structure, but also to draw inferences about the materials used to make an object. This is because to make an x-ray an object is exposed to radiation of a known energy level and the X-rays that pass through the object hit the detector (for digital anyway, it used to be film) that is placed under the object. How well the X-rays penetrate the object depends on the material it is made of. Areas on the X-ray that appear white are areas where the X-rays do not penetrate. This property is known as radio opacity. The X-ray below shows very clearly that there are spheres of roughly equal diameter on the interior of the object, which are responsible for the rattling noise. These spheres are made of a material that is blocking the x-rays more than the ceramic. We took a second X-ray of this object at an even higher energy level and because the spheres remained white, they are most likely made of lead.
This X-ray also shows details revealing how the object was made. Highlighted in blue below are thinner areas on the ceramic body that make a spiral pattern. This type of pattern is made when an object is made on some sort of wheel, although not necessary a fast wheel.
For more about Cypriot ceramics see this recent post on ceramics from Lapithos.