Gold and Quartz

ID	345
Mineral	Gold Quartz
Location	Breckenridge - California - United States of America
Fluorescence	LW-UV: close SW-UV: close
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Mindat data

ID	1720
Long ID	1:1:1720:2
Formula	`Au`
IMA Status	0 1
Other Occurrences	1) Primary hydrothermal veins 2) Volcanic-exhalative sulphide deposits 3) Alluvial and eluvial
Industrial	Electrical conductor, transparent reflective coating, jewelry, dentistry, coinage, decorative coatings
Diapheny	Opaque
Cleavage	None
Tenacity	malleable
Colour	Rich yellow, paling to whitish-yellow with increasing silver; blue & green in transmitted light (only thinnest folia [gold leaf])
Hardness (min)	2.5
Hardness (max)	3.0
Luminescence	None
Lustre	Metallic
About the name	Gold is one of the first minerals used by prehistoric cultures. The Latin name for this mineral was "aurum" and Jöns Jakob Berzelius used Au to represent the element when he established the current system of chemical symbols. The Old English word "gold" first appeared in written form about 725 and may further have been derived from "gehl" or "jehl". May be derived from Anglo-Saxon "gold" = yellow. (Known to alchemists as Sol.)
Streak	Shining yellow
Crystal System	Isometric
Cleavage Type	None Observed
Fracture type	Hackly
Morphology	Usually crude to rounded octahedra, cubes, and dodecahedra to 2 cm. Often elongated along [100] or [111] directions, forming herringbone and dendritic twins. Flattened {111} plates with triangular octahedral faces. Rarely as wires ([111] elongation); reticulated; dendritic; arborescent; filiform; spongy; also massive in rounded fragments, flattened grains and scales (gold dust).
Twinning	Common on (111) to give herringbone twins. Repeated on (111) to give stacks of spinel twins that form hexagonal wires.
UV	none
Thermal Behaviour	Melting Point: 1062.4° ± 0.8°
key_elements	0
shortcode_ima	Au
Group	Copper 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: € 25

Dimensions: Not registered

Weight: 27 g

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Notes:

Symbol	Element
Au	Gold
O	Oxygen
Si	Silicium

Gold and Quartz

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