Whetstone is a general term for various types of fine-grained, sedimentary rocks or novaculite used for sharpening knives and tools. They are characterized by a very dense, uniform texture that provides a consistent abrasive surface for honing blades. These stones are typically found in ancient sedimentary deposits that have undergone low-grade metamorphic hardening.
Is this whetstone?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch whetstone with a known reference. Whetstone sits at Mohs 5-7, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Grain size: Novaculite crystals are 3 to 5 microns.
- 3Pick out the mineralsComposition: Natural whetstones are typically quartz, such as novaculite. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: dull.
- 5Match the color rangeCompare against the expected color range: gray, white, brown, yellowish.
Often confused with
Whetstone vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside whetstone
Minerals reported to co-occur with whetstone. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5-7
- Density
- 2.6-2.8 g/cm³
- Luster
- Dull
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Industrial, Lapidary
- Host rock
- sedimentary strata
- Grain size
- Novaculite crystals are 3 to 5 microns
- Composition
- Natural whetstones are typically quartz, such as novaculite
Where rockhounds find whetstone
1 mapped spotsClassic worldwide localities
- Arkansas, USA
- Thuringia, Germany
- Belgium
- Japan
- Scotland
Field-hunting tip
Where it forms: sedimentary strata. If you start seeing quartz, clay minerals, calcite in float, you are in the right ground. In the U.S., the densest reported localities are in Connecticut. Start trip planning there.
More whetstone photos
Common questions
How do you identify whetstone?+
Where is whetstone found?+
Can I find whetstone in the United States?+
What rocks look like whetstone?+
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Find whetstone on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
