Rock Identifier
Yooperlite (Syenite clast containing fluorescent Sodalite) (Sodalite-bearing Syenite) — igneous
igneous

Yooperlite (Syenite clast containing fluorescent Sodalite)

Sodalite-bearing Syenite

Hardness: 5.5-6.0 Mohs; Color: Gray or mottled under natural light, bright orange/pink/red under 365nm UV light; Luster: Dull to vitreous; Structure: Massive/granular; Specific Gravity: 2.5-2.6

Hardness
5
Luster
Dull to vitreous
Identified More igneous →

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Physical properties

Hardness: 5.5-6.0 Mohs; Color: Gray or mottled under natural light, bright orange/pink/red under 365nm UV light; Luster: Dull to vitreous; Structure: Massive/granular; Specific Gravity: 2.5-2.6

Formation & geological history

Formed through volcanic activity resulting in syenite rocks rich in sodalite. The specific specimens found in Michigan were transported from Canada by glacial movement during the last ice age.

Uses & applications

Predominantly used for mineral collecting, lapidary arts (polishing/jewelry), and as a popular educational find for amateur geologists.

Geological facts

They were 'discovered' and named by Erik Rintamaki in 2017 on the shores of Lake Superior. While the rock is common in Canada, its presence as beach stones in Michigan's Upper Peninsula made it a viral sensation.

Field identification & locations

Identify using a 365nm UV flashlight at night; it will glow brilliantly despite looking like a normal gray stone in daylight. Commonly found on the beaches of Lake Superior.

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