Sphalerite, Marcasite and Siderite

ID	233
Mineral	Sphalerite Marcasite Siderite
Location	Negresti-Oas - Satu Mare - Romania
Fluorescence	LW-UV: close SW-UV: close
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Mindat data

ID	3727
Long ID	1:1:3727:9
Formula	`ZnS`
IMA Status	0 1
Discovery Year	1847
Diapheny	Transparent,Translucent
Cleavage	Perfect {011}
Tenacity	brittle
Colour	Yellow, light to dark brown, black, red-brown, colourless, light blue. green
Hardness (min)	3.5
Hardness (max)	4.0
Luminescence	Fluorescent and triboluminescent
Lustre	Resinous
About the name	Originally called blende in 1546 by Georgius Agricola (Georg Bauer). Known by a variety of chemical-based names subsequent to Agricola and before Glocker, including "zincum". Named Sphalerite in 1847 by Ernst Friedrich Glocker from the Greek σφαλεροζ "sphaleros" = treacherous, in allusion to the ease with which dark varieties were mistaken for galena, but yielded no lead.
Streak	Pale yellow to brown.
Crystal System	Isometric
Cleavage Type	Perfect
Fracture type	Conchoidal
Twinning	{111}
UV	Light colored sphalerite may fluoresce in blue or orange in LW. Fluoresces less strongly, sometimes not at all, in SW or MW.
key_elements	0
shortcode_ima	Sp
Group	Sphalerite Group

ID	2571
Long ID	1:1:2571:9
Formula	`FeS₂`
IMA Status	0 1
Other Occurrences	Most frequently found in sedimentary rocks and coal beds, as a replacement mineral forming fossils, it is a mineral of low-temperature, near-surface, environments, forming from acid solutions. Pyrite, the more stable form of FeS^2, forms under conditions of higher temperatures and lower acidity or alkaline environments.
Discovery Year	1845
Diapheny	Opaque
Cleavage	Distinct on {101}. {110} in traces.
Tenacity	brittle
Colour	Pale brass-yellow, tin-white on fresh exposures.
Hardness (min)	6.0
Hardness (max)	6.5
Lustre	Metallic
About the name	Early use of the word marcasite seems to have been unspecific. The word is Arabic or Moorish and was applied to pyrite and similar metallic bronze colored minerals. Walter Pope (1665) mentioned marcasite occurring in the mercury ores of the Idria Mine, Cividale del Friuli in the Julian Alps of Slovenia: "There are also several Marcasites and stones, which seem to have specks of Gold in them, but upon trial they say, they find none in them. These round stones are some of them very ponderous, and well impregnated with Mercury; others light, having little or none in them." The mercury ore at Idria does contain metallic golden specks of what is now called marcasite, but it also has metallic golden pyrite. Johnathan Hill used the name marcasite in 1771, but his usage was also indiscriminate and was a term for any massive "pyrites" or "mundic". In 1845, Wilhelm Karl von Haidinger defined marcasite as the mineral is known today.
Streak	Dark-gray to black.
Crystal System	Orthorhombic
Cleavage Type	Distinct/Good
Fracture type	Conchoidal,Sub-Conchoidal
Morphology	Crystals usually tabular on {010}, also pyramidal, faces often curved, frequently twinned; also stalactic, globular, or reniform with radiating internal structure.
Twinning	Common on {101}, forming "swallowtail" contact twins; this may be repeated to form stellate fivelings. Less common on {011}.
UV	Not fluorescent in ultraviolet light
Comment Luster	Frequently iridescence obscures the luster and color
shortcode_ima	Mrc
Group	Marcasite Group

ID	3647
Long ID	1:1:3647:0
Formula	`Fe(CO₃)`
IMA Status	0 1
Other Occurrences	Most often found in bedded sedimentary deposits with a biological component, with shales, clays and coal beds - suggesting that the siderite is biogenically created under low-oxygen and low-Ph conditions. It is also found in metamorphosed sedimentary rocks as more massively crystalline material, as a primary gangue mineral in hydrothermal deposits, and in pegmatites, including nepheline syenite pegmatites; as bog deposits.
Industrial	An ore of iron when found in sufficient volumes to be economically recoverable.
Diapheny	Translucent
Cleavage	Perfect on {10_11}.
Tenacity	brittle
Colour	Yellowish-brown to greyish-brown, pale yellow to tannish, grey, brown, green, red, black and, rarely, colourless; tarnished iridescent at times; colourless to yellow and yellow-brown in transmitted light.
Hardness (min)	3.5
Hardness (max)	4.5
Lustre	Vitreous
About the name	Named in 1845 by Wilhelm Karl von Haidinger from the Greek "σίδηρος" (sideros), "iron", in allusion to its composition.
Streak	White
Crystal System	Trigonal
Cleavage Type	Perfect
Fracture type	Irregular/Uneven,Conchoidal
Morphology	Crystals usually rhombohedral {10_11} or {011_2}, often curved or with composite faces; also more rarely thin to thick tabular {0001}, prismatic [0001] with {11_20}, or scalenohedral; most often found as massive material, either fine-grained in sedimentary settings or massively crystalline in metamorphic settings; may also be botryoidal or globular with a fibrous internal structure.
Twinning	On {01_12}, lamellar, uncommon, with translation gliding on {0001} or {10_11}. On {0001}, rare.
shortcode_ima	Sd
Group	Calcite Group

Price: € 15

Dimensions: Not registered

Weight: 537 g

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Notes:

Symbol	Element
C	Carbon
Fe	Iron
O	Oxygen
S	Sulfur
Zn	Zinc

Sphalerite, Marcasite and Siderite

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