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Apophyllite-(KF) (Fluorapophyllite)
Current inventory:  0 gems
 

Apophyllite-(KF)

  
Apophyllite
is named from the Greek word apophylliso for away from and leaf, in allusion to the way it exfoliats upon heating.

Discovered in 1800;   IMA status: Apophyllite-(KF) Valid (IMA redefined in 1978)

 

Chemistry

 

 

Chemical Formula:

KCa4Si8O20(F,OH) 8(H2O)

 

Hydrated Potassium Calcium Sodium Silicate Fluoride Hydroxide

Molecular Weight:

760.47 gm

Composition:

Potasium

4.37 %

K

5.26 %

K2O

 

Sodium

0.45 %

Na

0.61 %

Na2O

 

Calcium

21.08 %

Ca

29.50 %

CaO

 

Silicon

29.55 %

Si

63.21 %

SiO2

 

Hydrogen

0.01 %

H

0.12 %

H2O

 

Oxygen

42.29 %

O

 

 

 

Fluorine

2.25 %

F

2.25 %

F

 

 

- %

F

-0.95 %

-O=F2

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/H.01-20

Nickel-Strunz 10th Ed. ID:

9.EA.15

 

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings

Related to:

Apophyllite Group. Apophyllite-(KF) - Apophyllite-(KOH) Series.

Members of Group:

Apophyllite Group: Apophyllite-(KF), Apophyllite-(KOH), Apophyllite-(NaF), Carletonite

Varieties:

None

Synonyms:

Fluorapophyllite, IMA1976-001

 

 

Crystal Data

   

   

Crystallography:

Tetragonal - Ditetragonal Dipyramidal

Crystal Habit:

Crystals tabular to prismatic, to 20 cm, commonly pseudocubic with {100}, {001}, and modified by {111}; prism zone deeply striated || [001]; granular.

Twinning:

Rare on {111}.

 

 

Physical Properties

   

 

Cleavage:

Perfect on {001}, Imperfect on {110}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.0

Density:

2.33 - 2.4 (g/cm3)

Luminescence:

Usually none; some specimens may fluoresce pale green or yellow.

Radioactivity:

Barely Detectable; GRapi = 62.81 (Gamma Ray American Petroleum Institute Units)

 

 

Optical Properties

   

   

Color:

Colorless, White, Pink, pale Yellow, Green

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on cleavage {001}

Refractive Index:

1.530 - 1.538  Uniaxial ( + )

Birefringence:

0.0020

Dispersion:

High, may be anomalous

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

A secondary mineral in amygdules or druses in basalts; in cavities in granite; in tactite and other metamorphic rocks; a late-stage hydrothermal mineral in some mineral deposits.

Common Associations:

Calcite, Datolite, Pectolite, Quartz, Zeolites

Common Impurities:

Al, Na

Type Locality:

Lonault and Poona, southeast of Bombay, India

Year Discovered:

1800

View mineral photos:

Apophyllite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


According to the IMA,
Apophyllite is not actually a mineral. The IMA no longer recognizes Apophyllite as an official, individual  mineral name but only as the name of a group of minerals. The IMA approved names for these minerals are Apophyllite-(KF), Apophyllite-(KOH) and Apophyllite-(NaF). Some refer to them as Fluorapophyllite, Hydroxyapophyllite and Natroapophyllite respectively. I will continue to refer to these mineral specimens and gems simply as Apophyllite though. Apophyllite-(KF) is by far the most abundant and colorful of the three and is usually what is referred to when a mineral specimen or gemstone is labeled "Apophyllite."

Apophyllite is extremely rare as a gem because it is very brittle and fragile, with an extremely perfect and easy cleavage. Colorless Apophyllite gems are so devoid of any trace of color that they almost appear silvery. The green, iron-rich Apophyllite from India occurs in beautiful crystal groups.

There are many localities worldwide for finding Apophyllite, but exceptional colorless and green crystals are found in the Ahmadnagar, Bombay, Jalgaon, Nasik and Poona Districts, Maharashtra, India.
 

  
Apophyllite gems for sale:

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