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Graftonite with Sarcopside

#43827

Graftonite with Sarcopside

#43827
Availability
Sold
Size
3 x 2 x 1.5 cm - Thumbnail 
Formula
(Fe2+,Mn2+,Ca)3(PO4)2 (RRUFF)
Locality
Berg, Sollefteå, Ångermanland, Sweden
Tagged
phosphate , pegmatite mineral

Brownish red mass with laminations of Sarcopside. The two minerals are related but not as a series. Both contain ferrous iron (Fe+2). Very few if any primary phosphates crystallize with ferric iron (Fe+3), since most of the rock forming minerals such as schorl and biotite will hog it all. Rosemaryite (see this Special Edition update) is an exception. According to Moore (Min. Rec. 1973), Graftonite usually forms with Sarcopside as alternating lamellae, unless much lithium is present in the parent melt upon which Triphyllite will form and alternate with Graftonite (Palermo, Bull Moose). You will see this example with other specimens in this Special Edition.

This locality is a pegmatite in which Graftonite occurs as primary nodules. Graftonite is fairly common in complex, fractionated pegmatites and a brief survey of Mindat localities show this except for one occurence in a meteorite.

Graftonite is fairly resistant to weathering and thus does not usually form secondary phosphate minerals.

Graftonite

Formula
(Fe2+,Mn2+,Ca)3(PO4)2 
Crystal System
Monoclinic 
Crystal Habit
Massive - Granular, Lamellar 
Cleavage
Perfect, None, None 
Luster
Vitreous - Greasy 
Color
brown, pink, dark brown, reddish brown 
Streak
pale pink 
Class
Monoclinic - Prismatic 
Fracture
Uneven 
Hardness

Data courtesy of Webmineral.

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