metamorphic
Slate with Iron Staining
Low-grade Metamorphic Mudstone (Slate)
Hardness: 2.5-4; Color: Grey-green base with reddish-brown and orange iron oxide staining; Luster: Dull to pearly; Crystal structure: Microcrystalline (foliated); Cleavage: Perfect slaty cleavage; Specific gravity: 2.7-2.8
- Hardness
- 2
- Luster
- Dull to pearly
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 2.5-4; Color: Grey-green base with reddish-brown and orange iron oxide staining; Luster: Dull to pearly; Crystal structure: Microcrystalline (foliated); Cleavage: Perfect slaty cleavage; Specific gravity: 2.7-2.8
Formation & geological history
Formed through the low-grade regional metamorphism of shale or mudstone under high pressure and low temperature conditions. The iron staining occurs post-metamorphism through the oxidation (weathering) of minerals like pyrite or chlorite.
Uses & applications
Commonly used for roofing tiles, flooring, garden stones, billiard table tops, and laboratory bench tops due to its durability and cleavage.
Geological facts
Slate can be split into very thin sheets while maintaining its strength. The colors are caused by trace minerals; iron oxides create reds and yellows, while chlorite creates the green tones seen here.
Field identification & locations
Identify in the field by its planar layers (foliation) and the way it rings when lightly struck. It is commonly found in mountainous regions or areas with tectonic history like the Appalachian Mountains or Wales.
More like this
