- An unglazed piece of porcelain, such as a tile, used to test the characteristic streak of minerals by rubbing the mineral across the tile. Streak plates have a hardness of about 6.5 on the Mohs scale and cannot be used for testing harder minerals.
- See streak.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.