Name/Title
CalciteEntry/Object ID
2009.62.238Description
Description: Common Name: Calcite (Phanthom Gray)
Chemistry: CaCo3
Class: Carbonates
Location: Lei Yang, Hunan Province, China
Description: Large crystals (1.500"-1.00") in a large mass. Smokey gray to light violet with no visible matrix.
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.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
16 inDepth
8 inLength
18 inLocation
Category
PermanentMoved By
Ian CunninghamDate
August 28, 2022Location
Wall
EastBuilding
Freida Smith HallCategory
PermanentMoved By
Steve MillerDate
May 2, 2013Location
Cabinet
Case #62Wall
EastRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent
