A silver mask from a king's tomb was not what this page describes.
Known. The page tells of a gilt silver mask of Queen Malakaye.
The mask is of Nubian Queen Malakaye, dated 664 to 653 BC. Gilt silver means silver with gold on it. The page lists the mask with other Nubian objects recovered in the early 20th century and shown in a museum exhibition. It does not say where the mask lay in the ground.
The page does not say what is still argued.
https://www.ancient-origins.net/news-general/gold-and-gods-opens-window-rulers-ancient-nubia-002008