White chert is a microcrystalline variety of silica that typically forms as nodules within chalk or limestone formations. It is well-known to rockhounders for its characteristic conchoidal fracture and history as the primary material for stone tool-making, such as arrowheads and scrapers.
Is this white chert?
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 white chert with a known reference. White Chert sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. White Chert leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. White Chert typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, cream, grayish-white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, nodular, concretionary.
Often confused with
White Chert vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside white chert
Minerals reported to co-occur with white chert. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.65 g/cm³
- Colors
- Streak
- White
- Luster
- Waxy
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Massive, Nodular, Concretionary
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Decorative, Historical Tool-making
- Host rock
- Sedimentary (chalk and Limestone Beds)
- Typical price
- $1-20 for rough specimens, depending on size and inclusions
Where rockhounds find white chert
1 mapped spotsClassic worldwide localities
- United Kingdom
- France
- United States
- Denmark
- Belgium
Field-hunting tip
Look in sedimentary (chalk and limestone beds) country, the host setting where white chert typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a massive, nodular, concretionary habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Missouri. Start trip planning there.
Common questions
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Find white chert on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
