Properties of Epidote

Epidote is a mineral that belongs to the silicate group, and its chemical formula is generally represented as Ca2Fe·(Al,Fe)2O(OH)(SiO4)(Si2O7). It is a green to black mineral that commonly forms elongated, prismatic crystals or can be found in granular masses.

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Image of epidote mineral
Credit: Didier Descouens, CC BY 4.0, via Wikimedia Commons

The following table provides a comprehensive list of epidote properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).

Note: click on the button to switch between Metric and Imperial units.

Table of Epidote Properties
Physical Properties
Metric
Chemical FormulaCa2Fe·(Al,Fe)2O(OH)(SiO4)(Si2O7)
Molar Mass519.3 g/mol
Crystal SystemMonoclinic
Mohs Hardness6 - 6.5
Density3380 - 3490 kg/m3
ColorGray, apple green, brown, blue, or rose red
DiaphaneityTransparent to translucent
LusterVitreous (glassy), resinous, pearly
Cleavage[001] perfect, [100] imperfect
FractureUneven
StreakWhite

Note: unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)

Related Pages
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017.