the.com/iolite
a gem that changes color depending on which way you tilt it.
means Iolite is a gem-quality violet-blue variety of the mineral cordierite, prized for showing strikingly different colors when viewed from different angles.
from From the Greek "ion," violet (the flower), plus "lithos," stone — literally "violet stone," named for its blue-violet hue. There's a sailors' legend that Vikings used thin slices of iolite as a polarizing filter to locate the sun on overcast days, which is why it's sometimes called the "Viking compass stone"; this is a popular tale that's plausible in principle but not firmly proven by hard evidence.
- viking compass
- Norse sailors used it to find the sun through clouds
- name origin
- Greek 'ios' means violet, its signature hue
- also called
- water sapphire, despite no sapphire relation
- pleochroism
- shows three different colors from three angles
- polarizing trick
- filters light like natural sunglasses do
dichroite — alternative name for iolite mineral, named by haüy in 1801 for its two-colored appearance
water sapphire — iolite from sri lanka, historically called this due to blue color resembling sapphire
viking sun compass — theory that norse sailors used iolite crystals to navigate arctic waters by polarizing light