Name/Title
Chlorite in CalciteEntry/Object ID
2004.1.38Description
Assemblage Zone: pegmatite dikes
Chemical Composition: (Fe, Mg, Al)6(Si, Al)4O10
Crystal System: Hexagonal System
Description: Common Name: Chlorite on Calcite
Group Name: The clays and the Chlorite, Calcite is a group in self
Chemistry: (Fe, Mg, Al)6(Si, Al)4O10(OH)8, Iron Aluminum Magnesium Silicate Hydroxide.
Chemistry: CaCO3, Calcium Carbonate
Class: Disilicate on Carbonate
Location: Rio Grande do Sul, Brazil
Description: There is the green chlorite covering the dog tooth calcite crystals.
PHYSICAL CHARACTERISTICS:
Color is usually green but can also be white, yellow, red, lavender and black.
Luster is vitreous, dull or pearly.
Transparency: Crystals are translucent transparent.
Crystal System is monoclinic; 2/m.
Crystal Habits: Rarely in large individual barrel or tabular crystals with an hexagonal outline. Usually found as alteration products of iron-magnesium minerals and as inclusions in other minerals. Aggregates can be scaly, compact, platy and as crusts.
Cleavage is perfect in one direction, basal; not seen in massive specimens.
Fracture is lamellar.
Hardness is 2 - 3
Specific Gravity is variable from 2.6 - 3.4 (average to slightly above average)
Streak is pal green to gray or brown.
Other Characteristics: Cleavage flakes are flexible but not elastic.
Associated Minerals include garnets, biotite, quartz, magnetite, talc, serpentine, danburite, topaz and calcite, among many others.e.
Best Field Indicators color, cleavage, associations and crystal habits.
Fracture: lamellar
Hardness: 2 Gypsum
Luster: Glassy
Occurrence: Chlorite is commonly found in igneous rocks as an alteration product of mafic minerals such as pyroxene, amphibole, and biotite. Chlorite is a common mineral associated with hydrothermal ore deposits and commonly occurs with epidote, sericite, adularia and sulfide minerals. In this environment chlorite may be a retrograde metamorphic alteration mineral of existing ferromagnesian minerals, or it may be present as a metasomatism product via addition of Fe, Mg, or other compounds into the rock mass. Chlorite is also a common metamorphic mineral, usually indicative of low-grade metamorphism. It is the diagnostic species of the zeolite facies and of lower greenschist facies. It occurs in the quartz, albite, sericite, chlorite, garnet assemblage of pelitic schist. Within ultramafic rocks, metamorphism can also produce predominantly clinochlore chlorite in association with talc. Experiments indicate that chlorite can be stable in peridotite of the Earth's mantle above the ocean lithosphere carried down by subduction, and chlorite may even be present in the mantle volume from which island arc magmas are generated.
Chlorite occurs naturally in a variety of locations and forms. For example, chlorite is found naturally in certain parts of Wales in mineral schists.[1] Chlorite is found in large boulders scattered on the ground surface on Ring Mountain in Marin County, California.[2]
Notable Occurrences include Transvaal, South Africa; Zermatt, Switzerland; Guleman, Turkey; Lancaster Co., Pennsylvania, Brewster, New York; San Benito Co., California, USA and many other locallities world wid
The largest documented single crystals of calcite originated from Iceland, measured 7x7x2 m and 6x6x3 m and weighed about 250 tons.[7][8]
Calcite is a common constituent of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone.
Calcite is the primary mineral in metamorphic marble. It also occurs as a vein mineral in deposits from hot springs, and it occurs in caverns as stalactites and stalagmites.
Calcite may also be found in volcanic or mantle-derived rocks such as carbonatites, kimberlites, or rarely in peridotites. Lublinite is a fibrous, efflorescent form of calcite.
Rock Type: Sedimentary
Specific Gravity: 2.7
Streak: pale green to gray o
Variety: Chlorite is a general name for several minerals that are difficult to distinguish by ordinary methods. These minerals are all apart of the Chlorite Group of minerals. The chlorites are often, but not always considered a subset of the larger silicate group, The clays.
For practical reasons most of the chlorites will be considered here as a single mineral, chlorite. Chlorites are generally green and crystallize in the monoclinic symmetry system. They all have a basal cleavage due to their stacked structure. Chlorites typically form flaky microscopic crystals and it is this reason that they are sometimes included in the clay group of minerals. However chlorites also form large individual tabular to platy crystals that are unlike most of the other clay minerals.
Chlorites are most often known to mineral collectors as inclusions in or coatings on quartz, danburite, topaz, calcite and many other minerals. The inclusions are usually a very strong green color despite the small amount of material that actually constitutes the inclusion. These inclusions and coatings can be an enhancement but are more often a bane to what might have been a really valuable mineral specimen.
The chlorite inclusions in clear quartz are particularly interesting when they form as a coating on a crystal early in its development. Because if the crystal later grows larger, ie. out and around the chlorite coating, the effect will be to produce a phantomed crystal. A phantom is a crystal that appears to have a smaller crystal inside of it. Many times the interior "crystal" is indistinct or ghostly and thus the name phantom.
There are many minerals that make up the chlorites and thus many varieties. One variety is called kaemmererite and is a variety of the chlorite clinochlore. Sometimes kaemmererite is called chromian clinochlore because of the increase chromium content. It is the chromium that gives kaemmererite its bright lavender to deep crimson red color.
Calcite, which gets its name from "chalix" the Greek word for lime, is a most amazing and yet, most common mineral. It is one of the most common minerals on the face of the Earth, comprising about 4% by weight of the Earth's crust and is formed in many different geological environments. Calcite can form rocks of considerable mass and constitutes a significant part of all three major rock classification types. It forms oolitic, fossiliferous and massive limestones in sedimentary environments and even serves as the cements for many sandstones and shales. Limestone becomes marble from the heat and pressure of metamorphic events. Calcite is even a major component in the igneous rock called carbonatite and forms the major portion of many hydrothermal veins. Some of these rock types are composed of better than 99% calcite. Why would a collector be interested in such a common mineral? Because of its extraordinary diversity and beauty!Collection
Suomynona Mineral CollectionAcquisition
Accession
2004.1Source or Donor
Suomynona Mineral CollectionAcquisition Method
DonationDimensions
Width
10 inDepth
3 inLength
14 inWeight
4 ozDimension Notes
Dimension taken at widest pointsLocation
Category
PermanentMoved By
Ian CunninghamDate
August 28, 2022Location
Drawer
bottom tierShelf
south sideCabinet
case #62Wall
south of centerRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent