Mineral pseudomorph
Limonite after Pyrite (Prophecy Stone)
Limonite (FeO(OH)·nH2O) replacing Pyrite (FeS2)
Hardness: 4.0-5.5 (Mohs scale), Color: Dark brown to black, Luster: Sub-metallic to dull/earthy, Crystal Structure: Cubic or orthorhombic (inherited from pyrite), Cleavage: None, Specific Gravity: 3.0-4.3
- Hardness
- 4
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Physical properties
Hardness: 4.0-5.5 (Mohs scale), Color: Dark brown to black, Luster: Sub-metallic to dull/earthy, Crystal Structure: Cubic or orthorhombic (inherited from pyrite), Cleavage: None, Specific Gravity: 3.0-4.3
Formation & geological history
Formed through a process called pseudomorphism where original pyrite crystals are chemically replaced by iron oxides (limonite/goethite) over millions of years due to oxidation and hydration in sedimentary environments, specifically the White Desert of Egypt.
Uses & applications
Primarily used as a collector mineral and a 'meditation stone' in metaphysical communities. It has no major industrial or construction uses due to its brittle nature.
Geological facts
This specimen is a 'pseudomorph,' meaning 'false form.' While it looks like an iron-rich crystal, it has completely changed its chemical identity while keeping the shape of the original mineral. The most famous specimens come from the Farafra Oasis in Egypt.
Field identification & locations
Identify in the field by its distinct cubic or star-like 'spiky' shape and its high weight (density) relative to its size. It often leaves a yellow-brown streak on unglazed porcelain. Commonly found in desert regions where pyrite has oxidized.
More like this
Other mineral pseudomorph specimens
Blue Tiger's Eye
Silicon Dioxide (SiO2) with Crocidolite inclusions
Mineral (Pseudomorph)
Limonite pseudomorph after Pyrite
Goethite/Limonite FeO(OH)·nH2O
mineral
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
mineral
Tiger's Eye
Tiger's Eye (SiO2 with crocidolite inclusions)
mineral
Limonite (often after Pyrite)
Limonite (FeO(OH)·nH2O)
mineral
Goethite pseudomorph after Pyrite
Goethite (FeO(OH)) pseudomorph after Pyrite (FeS2)
mineral