Aragonite
ID: 53
Aragonite
Chemical Formula
CaCO₃
Hardness (Mohs)
3.5 - 4
Crystal System
Orthorhombic
Streak
White
Luster
Vitreous (glassy) to resinous.
Diaphaneity
Transparent to translucent
Color
Typically colorless, white, or pale yellow, but can also be gray, green, blue, pink, or brown.
Crystal Habit / Mode of Occurrence
Often occurs as prismatic or acicular (needle-like) crystals, frequently twinned, which can result in pseudohexagonal shapes. Also found in radiating, fibrous, stalactitic, and botryoidal forms.
Fun Facts
It's a polymorph of calcite, meaning it has the same chemical formula (CaCO3) but a different crystal structure; it's a major component of mollusk shells and coral skeletons.