Name/Title
Dogtooth CalciteEntry/Object ID
2015.1.25Description
Chemical Composition: CaCO3
Crystal System: Hexagonal System
Description: Common Name: Calcite (Dogtooth)
Chemistry: CaCO3
Group: Carbonates
Location: Carlin Trend, Nev.
Description: This specimen is a large piece of "dogtooth) calcite, with opaque white colored crystals with nice terminations. (hexagonal scalenehedrous) Some gray seen. Matrix is massive Calcite.
Physical Charateristics:
•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.
PHYSICAL CHARACTERISTICS:
•Color is blue-green, green, white, colorless, brown and yellow.
•Luster is vitreous in large crystals to dull in more compact forms.
•Transparency crystals are transparent to translucent.
•Crystal System is orthorhombic; mm2
•Crystal Habits include the bladed crystal form and the botryoidal form as the most common. The crystals are usually elongated and flat. The terminations are different at each end. One termination is blunted by a pedion face that is usually bevelled by several dome faces. The other end is pointed, being capped by a pyramid. The other common form is botryoidal producing a grape bunch texture. Often the botryoidal form has a cock's comb appearance showing rough crystal terminations.
•Cleavage is perfect in one direction.
•Fracture is conchoidal to subconchoidal.
•Hardness is slightly less than 5.
•Specific Gravity is approximately 3.4+ (above average)
•Streak is white.
•Associated Minerals include limonite, aurichalcite, calcite and smithsonite.
•Other Characteristics: strongly pyroelectric and piezoelectric.
•Notable Occurrences include Santa Eulalia and Mapimi, Mexico; New Mexico and New Jersey, USA: England and Zambia.
•Best Field Indicators are crystal habit, color, density and luster.
Fracture: conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Rock Type: Sedimentary
Specific Gravity: 2.7
Streak: whiteCollection
RAGM Mineral CollectionDimensions
Width
14-1/2 inDepth
6-1/2 inLength
22 inLocation
Location
Shelf
FS-13-CRoom
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Jillian Mather KettleyDate
June 17, 2025Notes
Location update while cleaningLocation
Shelf
Bottom cubby, right, Bottom cubby, rightBuilding
Freida Smith HallCategory
PermanentMoved By
Rawley WyattDate
June 26, 2015
