Andesine

Andesine is a plagioclase feldspar intermediate in composition between albite and anorthite.

In thin section, plagioclase feldspar grains often look like they’re sprinkled with dirt (PPL) or tiny confetti (XPL). You can find the explanation on the plagioclase feldspar page.

Physical Properties
Chemical formula (Na,Ca)(Si,Al)4O8
Class Tectosilicate
3D framework of linked tetrahedra
Crystal system Triclinic
Habit Tabular
Massive
Granular
Frequently twinned
from minerals.net
Color Colorless
Gray
Yellow-green
White
Hardness 7
Specific gravity 2.67
Cleavage Perfect {001}, good {010}
Fracture Uneven
Luster Vitreous
Transparency Transparent to translucent
Streak White
Optical Properties
PPL Colorless
Non-pleochroic
XPL 1st order gray
δ 0.008
after webmineral.com

Andesine in Hand Sample

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Andesine in Thin Section

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Further Reading

Andesine at mindat.org
Andesine at webmineral.com