Archive for the Epidote Group Category

  • Thulite

    Refractive Index : 1.701-1.695

    Optical Characteristic : DR, B+, AGG

    Specific Gravity : 3.09

    Formula : Ca2AI3(SiO4)3(OH)=Ca2AIAI1(SiO4)(Si2O7)O(OH)

    Crystal System : Orthorhombic

    Variety/Species : Zoisite

    Species/Group : Epidote Group

    Birefringence : 0.006

    Dispersion : 0.021

    Hardness : 6 to 7

    Toughness : Fair to poor

    Ultrasonic : Uaually safe

    Steam : Usually safe

    UV Long : Inert

    UV Short : Inert

    Pleochroism : 3 Colors

    Strength : Weak to moderate

    Pleochroism Colors : Weak [...]

  • Unakite

    Refractive Index : 1.74, 1.55, 1.52(All Spot)

    Optical Characteristic : AGG

    Specific Gravity : 3.00 + 0.20 – 0.15

    Formula : Varies with mineral content

    Crystal System : Rock

    Variety/Species : Unakite

    Species/Group : Epidote Group

    Birefringence : None

    Dispersion : N/A

    Hardness : 6 to 7

    Toughness : Poor to good

    Ultrasonic : Never

    Steam : Never

    UV Long : Inert

    UV Short : Inert

    Pleochroism : None

    Strength : [...]

  • Zoisite

     

    Refractive Index : 1.700-1.695

    Optical Characteristic : DR, Biaxial positive, AGG

    Specific Gravity : 3.35 (+.10 -.25)

    Formula : Ca2AI3(SiO4)3(OH) 

    Crystal System : Orthorhombic

    Variety/Species :
    Tanzanite – Transparent blue to violet to bluish purple
    Thulite – Translucent to opaque pink, often molted or streaked with gray or white, also called rosaline and uniolite
    Ruby in Zoisite – Translucent to opaque rock [...]