Certain stones, notably the peridot (or chrysolite) and the hessonite (or cinnamon stone), have an oily luster.
"A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public" by Frank Bertram Wade
Hessonite is rather a soft stone, its hardness being about that of quartz or 7, whilst the hardness of most garnet reaches 7.5.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 4" by Various
It is related to hessonite, or cinnamon-stone.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4" by Various