Name/Title
CalciteEntry/Object ID
78.63.19Description
Chemical Composition: CaCO3
Crystal System: Triclinic System
Description: Common Name: Calcite
Group Name: Carbonates
Location: Arizona
Chemistry: CaCO3
Description: Delmar described this specimen as a large tabular piece of rock with sharp(Scalenohedron) termminations on the Calcite crystals, on the side. Name:"Sharkstooth"
Calcite. Calcite is translucent white. Piece is from Arizona.
PHYSICAL CHARACTERISTICS:
• Color is extremely variable but generally white or colorless or with light shades of yellow, orange, blue, pink, red, brown, green, black and gray. Occasionally iridescent.
• Luster is vitreous to resinous to dull in massive forms.
• Transparency: Crystals are transparent to translucent.
• Crystal System is trigonal; bar 3 2/m
• Crystal Habits are extremely variable with almost any trigonal form possible. Common among calcite crystals are the scalenohedron, rhombohedron, hexagonal prism, and pinacoid. Combinations of these and over three hundred other forms can make a multitude of crystal shapes, but always trigonal or pseudo-hexagonal. Twinning is often seen and results in crystals with blocky chevrons, right angled prisms, heart shapes or dipyramidal shapes. A notch in the middle of a doubly terminated scalenohedron is a sure sign of a twinned crystal. lamellar twinning also seen resulting in striated cleavage surfaces. Pseudomorphs after many minerals are known, but easily identified as calcite. Also massive, fibrous, concretionary, stalactitic, nodular, oolitic, stellate, dendritic, granular, layered, etc. etc.
• Cleavage is perfect in three directions, forming rhombohedrons.
• Fracture is conchoidal.
• Hardness is 3 (only on the basal pinacoidal faces, calcite has a hardness of less than 2.5 and can be scratched by a fingernail).
• Specific Gravity is approximately 2.7 (average)
• Streak is white.
• Other Characteristics: refractive indices of 1.49 and 1.66 causing a significant double refraction effect (when a clear crystal is placed on a single line, two lines can then be observed), effervesces easily with dilute acids and may be fluorescent, phosphorescent, thermoluminescence and triboluminescent.
• Associated Minerals are numerous but include these classic associations: Fluorite, quartz, barite, sphalerite, galena, celestite, sulfur, gold, copper, emerald, apatite, biotite, zeolites, several metal sulfides, other carbonates and borates and many other minerals.
• Notable Occurrences include Pugh Quarry, Ohio; Rosiclare, Illinois; Franklin, New Jersey; Elmwood, Tennessee; Brush Creek and other Missouri, Wisconsin, Kansas and Oklahoma localities, USA; Andreasburg, Harz Mountains and Saxony, Germany; Brazil; Guanajuato, Mexico; Cornwall, Durham and Lancashire, England; Bombay area of India; Eskifjord, Iceland; many African localities as well as others around the world with their own unique varieties.
• Best Field Indicators are crystal habit, reaction to acid, abundance, hardness, double refraction and especially cleavage.
- See more at: http://www.galleries.com/Calcite#sthash.9blJZpmF.dpuf
Fracture: conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: t
Rock Type: Sedimentary
Specific Gravity: 2.65
Streak: white
Variety: 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!
With calcite so abundant and so widely distributed it is no wonder that it can be so varied. The crystals of calcite can form literally a thousand different shapes by combining the basic forms of the positive rhombohedron, negative rhombohedron, steeply, moderately and slightly inclined rhombohedrons, various scalahedrons, prism and pinacoid to name a few of the more common forms. There are more than 300 crystal forms identified in calcite and these forms can combine to produce the thousand different crystal variations. Calcite also produces many twin varieties that are favorites among twin collectors. There are also phantoms, included crystals, color varieties, pseudomorphs and unique associations. There simply is no end to the varieties of calcite.Collection
Delmar Smith Mineral CollectionDimensions
Width
14-3/8 inDepth
2-1/2 inLength
12-1/2 inDimension Notes
Dimension taken at widest pointsLocation
Location
Shelf
CS-F-2Room
Curation StorageBuilding
Crater Rock MuseumCategory
PermanentMoved By
Jillian Mather KettleyDate
February 21, 2024
