Where is Hornblende Schist found?

Hornblende Schist occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.

Where to find Hornblende Schist

Collecting tips

1. Look for Outcrops in Metamorphic Terrains. Hornblende schist is typically found in areas that have undergone significant regional metamorphism, such as mountain ranges, ancient shield areas, and eroded continental collision zones. Consult geological maps to identify such regions.
2. Identify Schistosity and Dark Color. Look for rocks with a distinct layered or foliated texture that can be easily split along planes. The dark green to black color, dominated by prismatic hornblende crystals, is a key indicator.
3. Examine Mineral Composition. Under a hand lens, identify the elongated, dark green to black hornblende crystals aligned in parallel. The presence of other minerals like plagioclase (whitish), quartz (glassy), or garnet (reddish, equant) can also be observed.
4. Distinguish from Amphibolite. While similar in mineralogy, hornblende schist has a much stronger and more pervasive schistosity than amphibolite, which tends to be more massive or weakly foliated.

Quick Check

Color:

Dark green to black

Luster:

Vitreous to sub-vitreous (hornblende), overall dull to somewhat shiny on foliation planes

Streak:

Grayish-green to colorless (for hornblende, but not practical for the rock)

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