metamorphic

Blue-green amphibolite (likely hornblende schist)

Amphibolite dominated by hornblende amphibole and plagioclase feldspar, with possible epidote/chlorite and magnetite

AI-generated identification · may be incorrect

Dark blue-green to black, coarse foliated/granular texture, subvitreous to dull luster, and no obvious crystal faces. Typical hardness is about 5–6 (locally higher); amphibolite is dense, commonly around 2.9–3.3 g/cm³, consistent with the reported heavy 6 cm specimen.

Identified September 1, 2026More metamorphic →

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At a glance

Common name: Blue-green amphibolite (likely hornblende schist)
Scientific name: Amphibolite dominated by hornblende amphibole and plagioclase feldspar, with possible epidote/chlorite and magnetite
Category: metamorphic
Identified: September 1, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common hand specimen; $30–$100 if unusually attractive, polished, or locality-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 mountain building. Most examples are Precambrian to Paleozoic or younger, depending on locality.

Uses & applications

Used as crushed aggregate, road stone, riprap, and occasionally dimension stone; attractive polished pieces are collected but are not usually valuable gemstones.

Geological facts

The blue-green color commonly comes from hornblende, while epidote or chlorite may add green tones; magnetite can make the rock unusually heavy or weakly magnetic.

Field identification & locations

Look for aligned amphibole grains or foliation, dense weight, and a dark green-black streak; a magnet test and hardness test help. Common in metamorphic belts worldwide, including Scandinavia, the Alps, India, Brazil, and North America.