Agate stone is preliminary lapped and does not require lapping after purchase.
Agate sharpening stones should be used with honing oil as lubricant. The stone does not absorb oil. Put a small amount (1-2 drops) of honing oil on the stone’s surface and spread it evenly over the stone with a finger. Remove the used lubricant with a paper towel.
The stone becomes finer over time. Refresh stone surface with a coarse dressing stone if the surface becomes glazed.
Agate whetstone is determined as the nephrite in petrography tests. Nephrite is an microgranular aggregate of the calcium, magnesium, and iron-rich amphibole minerals. Agate has fiber crystal structure, very high hardness (6-7 Mohs) and relatively low abrasive properties. Agate can be considered as "rasp-file".
Photos below are made with polarized-light microscope, yellow line is 500 micron long. Click to open high-resolution image.
If you have a question regarding this product, please feel free to ask.
Courtesy of Mr. Wizard. Please read chart explanation in README.