Silicified algae represents ancient cyanobacterial colonies where organic material has been replaced by microcrystalline quartz. Collectors often look for distinct layering or 'cabbage head' growth patterns known as stromatolites which indicate the original biological structure.
Is this silicified algae?
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 algae with a known reference. Silicified Algae 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 Algae leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Silicified Algae typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: tan, brown, gray, white, black, red.
- 5Look at form & habitTypical habit: massive.
Often confused with
Silicified Algae vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside silicified algae
Minerals reported to co-occur with silicified algae. 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
- Waxy
- Transparency
- Opaque
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Carbonate Rocks
- Typical price
- $5-50 for hand specimens, higher for display-grade fossils
Where rockhounds find silicified algae
1 mapped spotsClassic worldwide localities
- Wyoming, USA
- Western Australia
- Morocco
- Utah, USA
- Canada
Field-hunting tip
Look in sedimentary carbonate rocks country — that is the host setting where silicified algae typically forms. If you start seeing calcite, dolomite, quartz 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 Wyoming — start trip planning there.
Common questions
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Find silicified algae on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
