Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. mineral
8. calcite

Anotations

Scope note:

Transparent, naturally-occurring calcite crystal used in demonstrating the polarization of light. An oblong stone made of Iceland spar found in the wreck of a 16th-century English warship in 2013 has led archaeologists to speculate that the crystal is one and the same as the sunstone, a near-mythical navigational aid said to have been used by Viking mariners.