Grossular and Feldspar

ID	612
Mineral	Grossular Feldspar
Location	Kayes Region - Mali
Fluorescence	LW-UV: close SW-UV: close
Mindat.org	View Grossular information at mindat.org View Feldspar information at mindat.org

ID	1755
Long ID	1:1:1755:4
Formula	`Ca₃Al₂(SiO₄)₃`
IMA Status	0 1
Description	Garnet Group. Andradite-Grossular Series, Grossular-Katoite Series, Grossular-Uvarovite Series, Pyrope-Grossular Series.
Other Occurrences	Contact and regionally metamorphosed calcareous rocks. Rodingites
Industrial	Gem
Diapheny	Transparent,Translucent
Tenacity	brittle
Colour	Brown, orange, red, yellow, green, white, colorless, pink
Hardness (min)	6.5
Hardness (max)	7.0
About the name	Originally named "cinnamon stone" ("Kanelstein" in German) in 1803 by Abraham Gottlob Werner and renamed grossularite by Werner in 1808. Named for the colour of gooseberries (Ribes grossularium) as the original specimens were this colour.
Streak	White to pale Brownish white
Crystal System	Isometric
Cleavage Type	None Observed
Fracture type	Irregular/Uneven,Sub-Conchoidal
Morphology	Dodecahedra or trapezohedra, granular, compact, massive. May have hexoctahedral faces. Rarely tetrahexahedral or octahedral.
Twinning	Not observed
UV	Almost always non-fluorescent; may be a weak golden yellow (LW & SW) Some light green grossular garnets exhibit orange-red luminescence under long-wave and short-wave ultraviolet light. Results imply that chromium and manganese are the luminescence activators in grossular garnets, and vanadium is a powerful quencher.
shortcode_ima	Grs
Group	Garnet Group

ID	1624
Long ID	1:1:1624:3
Entry type	5
About the name	The name is derived from the German term 'Feldspat'. For centuries, miners generally referred to minerals and rocks as "Spat" if they had the property of being particularly easy to (completely) split. The perfection of cleavage was often evident from the existing, visible cleavage cracks and from the fact that fine flakes (“Spaten”) detached from the mineral or rock body when struck with a hammer. The term feldspar came into being around the middle of the 18th century when people in mineralogy learned to differentiate between the different types of minerals more precisely. There are various theories about the exact origin of this name. In 1783, for example, Urban Brückmann asked himself whether feldspar could have received its name based on its characteristic way of occurrence in the form of fields or patches in granite and other types of rock (never as entire veins, rocks, or mountains). René-Just Haüy, on the other hand, suggested in his 1804 work "Traité de minéralogie" that the name could have been chosen based on the fact that feldspar fragments were regularly found in the fields. The feldspar would therefore be understood as “spar from the fields” and an indication that feldspar gradually turned into arable soil through weathering.
shortcode_ima	Fsp

Price: € 6

Dimensions: Not registered

Weight: Not registered

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