igneous
Diabase (Greenstone)
Diabase (also known as Dolerite)
Hardness: 6-7 (Mohs scale), Color: Dark grey to greenish-black with iron-oxidized pitting, Luster: Dull/Sub-vitreous, Crystal structure: Fine-to-medium grained phaneritic/ophitic, Specific Gravity: 2.7-3.3
Identified More igneous →
Explore Diabase (Greenstone) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Mohs scale), Color: Dark grey to greenish-black with iron-oxidized pitting, Luster: Dull/Sub-vitreous, Crystal structure: Fine-to-medium grained phaneritic/ophitic, Specific Gravity: 2.7-3.3
Formation & geological history
Formed from the cooling of mafic magma in shallow intrusive bodies like dikes or sills. The greenish tint often suggests low-grade metamorphism (greenschist facies) or chloritization of primary minerals over millions of years.
Uses & applications
Commonly used as crushed stone for road construction (riprap), high-quality railroad ballast, and decorative building stone or monuments.
Geological facts
Diabase is the primary rock type of the famous Hudson River Palisades in New York and New Jersey. It is chemically similar to basalt but cooled more slowly underground.
Field identification & locations
Identified by its dense, 'heavy' feel relative to its size and dark greenish-grey weathered surface with orange-brown iron spots. Often found in riverbeds or glacial tills in volcanic regions.
