Calcite, Sphalerite and Marcasite

ID	461
Mineral	Calcite Sphalerite Marcasite
Location	Becke-Oese quarry - Hemer - Sauerland - Germany
Fluorescence	LW-UV: close SW-UV: close
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Mindat data

ID	859
Long ID	1:1:859:4
Formula	`Ca(CO₃)`
IMA Status	0 1
Other Occurrences	Found in most geologic settings and as a later forming replacement mineral in most other environments in one form or another, it is most common as massive material in limestones and marbles. It forms as chemical sedimentary deposits as limestone, can be regionally or contact metamorphosed into marbles and rarely forms igneous rocks (carbonatites). Also is a common gangue mineral in hydrothermal deposits.
Industrial	Mined extensively for a wide variety of uses ranging from lime (cement) to limestone and marble building stones and aggregates, agricultural supplements and optical calcite.
Diapheny	Transparent,Translucent
Cleavage	Perfect on {10_11}.
Tenacity	brittle
Colour	White, Yellow, Red, Orange, Blue, Green, Brown, Gray etc.
Hardness (min)	3.0
Hardness (max)	3.0
Luminescence	Fluorescent
Lustre	Vitreous
About the name	Ancient name. Named as a mineral by Gaius Plinius Secundus (Pliny the elder) in 79 from Calx, Latin for Lime.
Streak	White
Crystal System	Trigonal
Cleavage Type	Perfect
Fracture type	Conchoidal
Morphology	Over 800 different forms have been described. Most commonly as acute rhombohedrons or prismatic with scalenohedral terminations, or combinations of the two.
Twinning	At least four twin laws have been described, the most common being when the twin plane and the composition plane are {01_12}. Also common with twinning on {0001} with {0001} as the compositional surface, producing re-entrant angles. Uncommon with {10_11} or {02_21} as twin planes, producing somewhat heart-shaped crystals ("butterfly" twins).
UV	May be fluorescent under LW UV, mid-range UV or SW UV as well as under X-rays, cathode rays and even sunlight, in a number of colors and shades, commonly an intense red under SW with Mn as an activator (such as at Franklin, New Jersey, USA, and Långban in Sweden.
Comment Luster	Pearly on cleavage and {0001}. Can be dull or earthy in chalk variety.
shortcode_ima	Cal
Group	Calcite Group

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

Price: € 40

Dimensions: Not registered

Weight: Not registered

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

Calcite, Sphalerite and Marcasite

Mindat data

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