metamorphic

Dark green amphibolite (likely hornblende schist)

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar, with possible biotite, epidote, and magnetite

AI-generated identification · may be incorrect

Hardness about 5.5–6; dark greenish-black, speckled, and weakly foliated with a dull to subtly glinting luster. Amphibole grains commonly form elongated crystals; cleavage is distinct in amphibole but the rock breaks irregularly. Specific gravity is typically 2.9–3.2.

Identified September 6, 2026More metamorphic →

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At a glance

Common name: Dark green amphibolite (likely hornblende schist)
Scientific name: Amphibolite; chiefly hornblende amphibole and plagioclase feldspar, with possible biotite, epidote, and magnetite
Category: metamorphic
Identified: September 6, 2026
Method: Standard

AI Estimated Value

About $1–$10 for an ordinary hand specimen; $10–$30 if polished, unusually attractive, or professionally labeled.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed when basaltic or gabbroic rock underwent medium- to high-grade regional metamorphism, commonly during Precambrian or Paleozoic mountain building. The Montreal-area region contains metamorphic rocks and glacially transported erratics, so local origin is plausible but not certain.

Uses & applications

Used as crushed aggregate, road stone, riprap, and occasionally decorative stone. Attractive polished pieces may be sold as ornamental material, but this specimen is not typically a gemstone.

Geological facts

The green color generally reflects iron- and magnesium-rich hornblende. It can resemble greenstone, basalt, or serpentinite; amphibolite is usually heavier and more crystalline than basalt.

Field identification & locations

Look for a dense, dark green-black rock with visible interlocking grains and possible planar fabric; a streak is usually grayish, and it is not scratched easily by a steel knife. Common in metamorphic belts and as glacial erratics around southern Quebec.