could you provide a link to the painting/sculpture?
Here are some sites on the elements of art.
Since you did not say who is the artist, I am unable to give you further information. After looking at these sites if you need more help, please repost.
Is it the metal relief covered in gold? Hrmony is not an element of art. The elements of art here are:
Line: because the picture is covered in gold, line is the main element that contributes to the overall success of the design. Line is used to bring forth the subject of this work and also outline the background setting. the subject of Madonna and her child is outlined and emphasized through the use of thin line in their overall shape, facial and bodily features (eyes, nose, mouth, ears, hands and legs), hair, halos, clothing and jewelry details. In the bottom right corner, line is used to outline and decorate a vase. In the background, line draws a large arch supported by elegant columns.
Color: the only color present is gold, perhaps used to emphasize its religious importance or simply draw the viewer's attention in its direction.
SHape and form: both figures appear to be three-dimensional and hold natural human figure.
Space: the majority of the space is taken by madonna and her child, thus emphasizing their importance.