Fluorite and Quartz

ID	2
Mineral	Fluorite Quartz
Location	Cavnic Mine - Cavnic - Maramures - Romania
Fluorescence	LW-UV: close SW-UV: close
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Mindat data

ID	1576
Long ID	1:1:1576:5
Formula	`CaF₂`
IMA Status	0 1
Other Occurrences	Hydrothermal veins; cavities in sedimentary rocks; as a cementing material in sandstones; as hot springs deposits.
Industrial	Flux in steel making; source of fluorine
Discovery Year	1529
Diapheny	Transparent
Cleavage	Perfect on {111}, very easy.
Tenacity	brittle
Colour	Purple, lilac, golden-yellow, green, colourless, blue, pink, champagne, brown. See also https://www.mindat.org/mesg-631877.html
Hardness (min)	4.0
Hardness (max)	4.0
Luminescence	Fluorescent, Short UV=blue, Long UV=blue.
Lustre	Vitreous
About the name	Named in 1797 by Carlo Antonio Galeani Napione from the Latin, fluere = "to flow" (for its use as a flux). The term fluorescence is derived from fluorite, which will often markedly exhibit this effect. The element fluorine also derives its name from fluorite, a major source of the element.
Streak	White
Crystal System	Isometric
Cleavage Type	Perfect
Fracture type	Splintery,Sub-Conchoidal
Morphology	Fluorite has seven main crystal forms: the most common Are the cube {100}, octahedron {111} and dodecahedron {110}; these forms having fixed Miller indices); and the tetrahexahedron {hk0}, trapezohedron {h11}, trisoctahedron {hhl} and hexoctahedron {hkl} (less common to quite rare crystal forms, having variable Miller indices). Combinations of two or more of these forms are common. The cuboctahedron (combined cube and octahedron) is less common than the combination of a cube and a docecahedron, the cubododecahedron. The faces of some crystal forms are more easily etched by nature than other faces, although this also depends on other parameters, and so none of the forms will always be smooth. Not all crystal faces will always be present, and sometimes certain faces are more developed than others, even within the same crystal form. Consequently, elongated crystals of fluorite have been observed." Crystals distorted at times by unequal development of faces, as of {013}. Often markedly composite; minute cubes aggregated to form an octahedron at times or as an overgrowth of crystals upon the corners of an earlier formed crystal of differing habit. Massive; compact; earthy, columnar (rare), or in globular aggregates; botryoidal (rare). For the Goldschmidt images we currently show the following habits with the crystallographic forms denoted here: no. 1 : a cube {100} no. 2 : an octahedron {111} no. 3 : a dodecahedron {110} no. 12: a cube {100}, modified by a hexoctahedron {421} no. 45: a cube {100}, highly modified by a dodecahedron {110}, two tetrahexahedrons: {210} and {310}, and a trapezohedron {211} no. 66: an octahedron {111}, modified by a dodecahedron {110} and a trisoctahedron {221}
Twinning	On {111}, usually as interpenetrating cubes (e.g., Strzegom, Poland), but also as contact spinel twins (e.g. Naica, Mexico and Chumar Bakhoor, Pakistan).
UV	Blue under LW-UV, due to Eu²⁺; other colors caused by different activators (white & cream - organic matter). Red (Mapimi, Mexico), pink (Doña Ana claims, AZ), white (Sterling Hill, NJ). Green response points to ytterbium (Siddike et al. 2003). May also be phosphorescent.
Thermal Behaviour	Melting point 1360°C.
Comment Luster	Dull when massive
shortcode_ima	Flr
Group	Fluorite Group

ID	3337
Long ID	1:1:3337:0
Formula	`SiO₂`
IMA Status	0 1
Other Occurrences	Most of them...
Industrial	Ore for silicon, glassmaking, frequency standards, optical instruments, silica source for concrete setting, filtering agents as sand. A major component of sand.
Diapheny	Transparent,Translucent
Cleavage	The rhombohedral cleavage r{10_11} is most often seen, there are at least six others reported.
Tenacity	brittle
Colour	Colorless, purple, rose, red, black, yellow, brown, green, blue, orange, etc.
Hardness (min)	7.0
Hardness (max)	7.0
Luminescence	Triboluminescent
Lustre	Vitreous
About the name	Quartz has been known and appreciated since pre-historic times. The most ancient name known is recorded by Theophrastus in about 300-325 BCE, κρύσταλλος or kristallos. The varietal names, rock crystal and bergcrystal, preserve the ancient usage. The root words κρύοσ signifying ice cold and στέλλειυ to contract (or solidify) suggest the ancient belief that kristallos was permanently solidified ice. The earliest printed use of "querz" was anonymously published in 1505, but attributed to a physician in Freiberg, Germany, Ulrich Rülein von Kalbe (a.k.a. Rülein von Calw, 1527). Agricola used the spelling "quarzum" (Agricola 1530) as well as "querze", but Agricola also referred to "crystallum", "silicum", "silex", and silice". Tomkeieff (1941) suggested an etymology for quartz: "The Saxon miners called large veins - Gänge, and the small cross veins or stringers - Querklüfte. The name ore (Erz, Ertz) was applied to the metallic minerals, the gangue or to the vein material as a whole. In the Erzgebirge, silver ore is frequently found in small cross veins composed of silica. It may be that this ore was called by the Saxon miners 'Querkluftertz' or the cross-vein-ore. Such a clumsy word as 'Querkluftertz' could easily be condensed to 'Querertz' and then to 'Quertz', and eventually become 'Quarz' in German, 'quarzum' in Latin and 'quartz' in English." Tomkeieff (1941, q.v.) noted that "quarz", in its various spellings, was not used by other noted contemporary authors. "Quarz" was used in later literature referring to the Saxony mining district, but seldom elsewhere. Gradually, there were more references to quartz: E. Brown in 1685 and Johan Gottschalk Wallerius in 1747. In 1669, Nicolaus Steno (Niels Steensen) obliquely formulated the concept of the constancy of interfacial angles in the caption of an illustration of quartz crystals. He referred to them as "cristallus" and "crystallus montium". Tomkeieff (1941) also noted that Erasmus Bartholinus (1669) used the various spellings for "crystal" to signify other species than quartz and that crystal could refer to other "angulata corpora" (bodies with angles): "In any case in the second half of the XVIIIth century quartz became established as a name of a particular mineral and the name crystal became a generic term synonymous with the old term 'corpus angulatum'."
Streak	White
Crystal System	Trigonal
Cleavage Type	Poor/Indistinct
Fracture type	Conchoidal
Twinning	Dauphiné law. Brazil law. Japan law. Others for beta-quartz...
Thermal Behaviour	Transforms to beta-quartz at 573° C and 1 bar (100 kPa) pressure.
shortcode_ima	Qz

Price: € 20

Dimensions: Not registered

Weight: Not registered

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Notes:

Symbol	Element
Ca	Calcium
F	Fluorine
O	Oxygen
Si	Silicium

Fluorite and Quartz

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