Clinozoisite

Clinozoisite is a silicate mineral recognized among collectors for its crystal form and distribution, with known Chinese sources.

Mohs 6.5
Vickers (~) 820 HV
Knoop (~) 870 HK
Geological setting
MetamorphicSkarn
Element composition by mass

Formula: Ca₂Al₃(SiO₄)(Si₂O₇)O(OH) · molar mass: 454.35 g/mol

O 45.78%
Si 18.54%
Al 17.82%
Ca 17.64%
H 0.22%

Computed from atomic weights (IUPAC 2021). Site-occupancy groups (Fe,Mn) split equally.

GroupEpidote Group
Related members: Epidote · Zoisite · Tanzanite
Mohs Hardness 6.5

Clinozoisite sits at 6.5 on the Mohs scale — harder than glass; scratches steel.

Colors:
Streak
White
Crystal system
Monoclinic
SilicatesSilicates (Sorosilicates)
TL;DR · 1 min read
Clinozoisite (Ca₂Al₃(SiO₄)(Si₂O₇)O(OH)) is the monoclinic counterpart of orthorhombic zoisite — same chemistry, different crystal system. It is closely related to epidote but has lower iron content.

Clinozoisite (Ca₂Al₃(SiO₄)(Si₂O₇)O(OH)) is the monoclinic counterpart of orthorhombic zoisite — same chemistry, different crystal system. It is closely related to epidote but has lower iron content. Clinozoisite forms in low-grade metamorphic rocks and contact-aureole skarns. Italian Alps and Japan yield gem-quality material.

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