Silicified lignite is a form of petrified wood where the organic plant structure has been replaced by microcrystalline quartz. Collectors often look for visible tree ring patterns or bark texture preserved within the chalcedony matrix. It is highly valued in lapidary for its ability to take a high polish and its varied, intricate patterns.
Is this silicified lignite?
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 silicified lignite with a known reference. Silicified Lignite 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. Silicified Lignite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Silicified Lignite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, black, gray, tan, red, yellow.
- 5Look at form & habitTypical habit: massive.
Often confused with
Silicified Lignite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Silicified Lignite and waxy on Agate.
How to tell apart: Luster reads vitreous on Silicified Lignite and waxy on Jasper.
How to tell apart: Luster reads vitreous on Silicified Lignite and waxy on Flint Nodules.
Often found alongside silicified lignite
Minerals reported to co-occur with silicified lignite. 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
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary
- Typical price
- $5-100 depending on quality and size
Where rockhounds find silicified lignite
1 mapped spotsClassic worldwide localities
- Petrified Forest National Park, USA
- Arizona, USA
- Madagascar
- Argentina
- Greece
Field-hunting tip
Look in sedimentary country — that is the host setting where silicified lignite typically forms. If you start seeing quartz, chalcedony, opal in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada — start trip planning there.
Common questions
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Find silicified lignite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
