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0 item @ $0.00  

Pegmatite Minerals

Friday, 31 October 2014 06:00 PM

Pegmatites are located all over the world and have have produced not only ore minerals but scientifically important rare mineral species. We will take a look at these minerals, mostly rare species, as well as introduce you to the many complexities of these interesting geological deposits.

Orthoclase

#PD40486
Locality
Pikes Peak Granite, Park Co., Colorado, United States 
Formula
K(AlSi3)O8 
Availability
Sold
Size
9 x 6 x 5 cm - Sm Cabinet 
Tagged
pegmatite mineral  

Just a neat old Foote Minerals specimen showing good crystals.


Orthoclase

Formula
K(AlSi3)O8 
Crystal System
Monoclinic 
Crystal Habit
Prismatic, Massive - Granular, Blocky 
Cleavage
Perfect, Good, None 
Luster
Vitreous (Glassy) 
Color
colorless, greenish, grayish yellow, white, pink 
Streak
white 
Class
Monoclinic - Prismatic 
Fracture
Uneven 
Hardness
Collection
Phillips Collection

Palermoite

with Goedkinite - #40404
Locality
Palermo mine, Groton, Grafton Co., New Hampshire, United States 
Formula
Li2SrAl4(PO4)4(OH)4 
Availability
Sold
Size
2 x 1.5 x 1.5 cm - Thumbnail 
Tagged
phosphate , pegmatite mineral  
Special Info
Type Locality 

Colorless, striated prismatic crystals to 1mm. Fairly rich.


Palermoite

Formula
Li2SrAl4(PO4)4(OH)4 
Crystal System
Orthorhombic 
Crystal Habit
Fibrous, Aggregates 
Cleavage
Perfect, Distinct, None 
Luster
Vitreous - Adamantine 
Color
colorless, white 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Splintery 
Hardness
5.5 
Collection
Phillips Collection
Special Info
Type Locality

Palermoite

#PD40416
Locality
Palermo mine, Groton, Grafton Co., New Hampshire, United States 
Formula
Li2SrAl4(PO4)4(OH)4 
Availability
Sold
Size
2 x 2 x 2 cm - Thumbnail 
Tagged
phosphate , pegmatite mineral  
Special Info
Type Locality 

This specimen contains several 0.5 to 1mm colorless, striated crystals.


Palermoite

Formula
Li2SrAl4(PO4)4(OH)4 
Crystal System
Orthorhombic 
Crystal Habit
Fibrous, Aggregates 
Cleavage
Perfect, Distinct, None 
Luster
Vitreous - Adamantine 
Color
colorless, white 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Splintery 
Hardness
5.5 
Collection
Phillips Collection
Special Info
Type Locality

Perhamite

#PD40403
Locality
Emmons quarry, Oxford, Co., Maine, United States 
Formula
Ca3Al7.7Si3P4O23.5(OH)14.1·8H2
Availability
Sold
Size
2 x 2 x 1.5 cm - Thumbnail 
Tagged
phosphate , pegmatite mineral  

White rosettes of Perhamite to 1mm. Perhamite is relatively rare occuring mostly in granitic pegmatites, but not restricted to them.


Perhamite

Formula
Ca3Al7.7Si3P4O23.5(OH)14.1·8H2
Crystal System
Hexagonal 
Crystal Habit
Platy 
Cleavage
Perfect, None, None 
Luster
Vitreous (Glassy) 
Color
light brown, white 
Streak
white 
Class
Hexagonal - Dihexagonal Dipyramidal 
Hardness
Collection
Phillips Collection
Mineralpedia
View Perhamite
On Dakota Matrix
Previously Sold Perhamite
On Dakota Matrix
Other Available Perhamite
WebMineral
View Perhamite
Mindat
View Perhamite
SOLD
Petalite - 39092
Petalite - 39092

Petalite

#39092
Locality
Rubicon mine, Karibib dist., Erongo, Namibia 
Formula
LiAlSi4O10 
Availability
Sold
Size
4.5 x 4 x 4 cm - Miniature 
Tagged
pegmatite mineral  

A pinkish mass of crystalline Petalite.


Petalite

Formula
LiAlSi4O10 
Crystal System
Monoclinic 
Crystal Habit
Massive 
Cleavage
Perfect, Imperfect, None 
Luster
Vitreous - Pearly 
Color
colorless, gray, yellow, yellow gray, white 
Streak
colorless 
Class
Monoclinic - Prismatic 
Fracture
Brittle - Conchoidal 
Hardness
6-6.5 
Mineralpedia
View Petalite
On Dakota Matrix
Previously Sold Petalite
On Dakota Matrix
Other Available Petalite
WebMineral
View Petalite
Mindat
View Petalite

Petalite

#PD40497
Locality
Londonderry Lithium deposit, Western Australia, Australia 
Formula
LiAlSi4O10 
Availability
Sold
Size
5 x 3 x 3 cm - Miniature 
Tagged
pegmatite mineral  

Dr, David London of University of Oklahoma has shown that pegmatite formation under conditions of silica (quartz) saturated conditions, the lithium aluminum silicates petalite, spodumene and eucryptite are good indicators of the temperature and pressure of formation. Spodumene at equilibrium occurs at high pressure, while petalite at high temperatures, But upon cooling, spodumene is sometimes seen as replacing petalite.

In this specimen thin white laminations can be seen within the otherwise colorless matrix. This is possibly the sort of replacement London has described on pages 55-58 of his "Pegmatites" - a highly recommended resource. Optical work would be required to determine if this replacement occured in this particular specimen.


Petalite

Formula
LiAlSi4O10 
Crystal System
Monoclinic 
Crystal Habit
Massive 
Cleavage
Perfect, Imperfect, None 
Luster
Vitreous - Pearly 
Color
colorless, gray, yellow, yellow gray, white 
Streak
colorless 
Class
Monoclinic - Prismatic 
Fracture
Brittle - Conchoidal 
Hardness
6-6.5 
Collection
Phillips Collection
Mineralpedia
View Petalite
On Dakota Matrix
Previously Sold Petalite
On Dakota Matrix
Other Available Petalite
WebMineral
View Petalite
Mindat
View Petalite

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