Labradorite
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Labradorite is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect.
Labradorite in a polished rock slab
Spectrolite with purple, pink, and orange iridescence
Polished block from Madagascar
Detail of labradorite
Plagioclase
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Plagioclase is a series of tectosilicate minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solut
Labradorite
…mineral first identified in Labrador, Canada, which can display an iridescent effect (schiller). Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most…
A photomicrograph of a plagioclase crystal (gray) under cross polarized light. The plagioclase crystal shows a distinct banding effect called polysynthetic twinning.
Plagioclase displaying cleavage (unknown scale)
In volcanic rocks, fine-grained plagioclase can display a "microlitic" texture of many small crystals.