Epidote Vs. Prehnite

Epidote is a popular mineral composed of calcium aluminium iron silicate.^[1] Prehnite is also a popular gemstone and its chemical composition is calcium aluminum silicate.^[2]

Quick Facts on Differences of Epidote and Prehnite

For a quick recap of the differences epidote and prehnite:

• While both epidote and prehnite can be translucent or transparent, epidote can be opaque.
• In terms of crystallography, epidote is monoclinic while prehnite is orthorhombic.
• For chemical formulas, epidote can be Ca2(Al or Fe)2(SiO4)3(OH) while prehnite is Ca2Al2Si3O12(OH).
• While both epidote and prehnite can be pearly or vitreous, in terms of luster, epidote can be dull or resinous and prehnite can be waxy.
• While both epidote and prehnite can be commonly green or yellow, epidote is often brown or red.
• Epidote's rarity is less rare than prehnite.
• Epidote's specific gravity is higher than prehnite - epidote ranges from 3.21 to 4.2 and prehnite ranges from 2.8 to 2.88.

Quick Facts on Similarities of Epidote and Prehnite

The similarities of epidote and prehnite include:

• Epidote and prehnite both streak white.
• Epidote's hardness overlaps with prehnite - epidote ranges from 6 to 7 and prehnite ranges from 6 to 6.5 on the Moh's scale.

Summary of Epidote

Epidote is a mineral that belongs to the sorosilicate group. It is a common mineral that is found in metamorphic, igneous and sedimentary rocks. Epidote is typically green, but it can also be yellow-brown, black or colorless. The mineral has a hardness of 6 to 7 on the Mohs scale and has a vitreous to resinous luster. Epidote is commonly found in prismatic or tabular crystal habit and can also occur in massive or granular form.

Summary of Prehnite

Prehnite is a silicate mineral that is typically found in basaltic rocks and hydrothermal veins. It was first discovered in South Africa in 1788 and was named after the Dutch mineralogist, Colonel Hendrik von Prehn. Prehnite is a translucent to transparent mineral that can range in color from pale green to yellow, gray, or white. It is often found in aggregates or as crusts on other minerals.

Table Comparison of Epidote vs Prehnite