This section is from the book "School Needlework. A Course of Study in Sewing designed for use in Schools", by Olive C. Hapgood. Also available from Amazon: School Needlework: A Course Of Study In Sewing Designed For Use In Schools.
Emery is a variety of corundum, and is ranked among the hardest of minerals. It derives its name from Cape Emeri on the island of Naxos, Grecian Archipelago, where the best variety is obtained. It is also found in a number of places in the United States.
It is used for polishing metals. The stone is crushed and sifted into powder of different fineness.