Apophyllite | Gemopedia

Apophyllite is divided into three distinct species, fluorapophyllite, hydroxyapophyllite and natroapophyllite, depending on their chemical composition. It was once considered to be a single mineral, so if chemical composition is not yet determined specimens will still be referred to as apophyllite. It is commonly found as glassy prismatic, blocky, or tabular white to grayish or light pastel crystals. The name apophyllite comes from the Greek word meaning "leafs off," referring to its tendency to flake when heated.
Alternate
Names
Fisheye Stone, Apophyllite-(KF)
Colors
Colorless, White, Reddish, Pink, Pale Yellow, Bluish, Green

Apophyllite Classification

Common Name

Apophyllite

Species

Apophyllite

Variety

Colors

Colorless, White, Reddish, Pink, Pale Yellow, Bluish, Green

Alternate Names

Fisheye Stone, Apophyllite-(KF)

Gemstone Groups

Key Separations

RI, birefringence, possible florescence

Comments

Apophyllite Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.535-1.537

Birefringence

0-0.002

Optic Character

Uniaxial

Optic Sign

Positive or Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: inert to moderate yellowish white or green
LWUV: Inert to moderate yellow or yellowish white

CCF Reaction

Pleochroism

None

Dispersion

Strength: strong fire

Comments

Apophyllite Chemistry & Crystallography

Chemical Name

hydrated potassium calcium silicate fluoride hydroxide

Chemical Formula

KCa4Si8O20(F,OH).8H2O

Synthesis

Crystal System

Tetragonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Apophyllite Characteristic Physical Properties

Hardness

4.5-5

Streak

White

Specific Gravity

2.3-2.5

Toughness

Poor

Inclusions

Luster

Vitreous

Stability

Poor

Fracture

Uneven

Cleavage

Perfect, in one direction, good in one direction

Comments

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