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.
