Built-in image resources that may be used as the ThumbnailSource parameter for the tile definitions are:

GraphicImage resource for ThumbnailSource
areachart.png
barchart.png
columnchart.png
costSavings.png
energyStar.png
linechart.png
piechart.png
table.png

Built-in image resources that may be used in table columns when they are set to image type.

GraphicImage resource for table columns
Barrel.png
Building.png
Car.png
Co2.png
Computer.png
Emission.png
Group.png
Laptop.png
Money.png
Tree.png