Name/Title
Quartz / ChrysocollaEntry/Object ID
2009.62.219Description
Description: Common Name: Quartz / Chrysocolla
Chemistry: SiO2 , Silicon dioxide / Cu2H2Si2O5(OH)4, Copper Silicate
Class: Silicates
Subclass: Tectosilicates
Group: Quartz
Location: Milpillas Mine, Mexico
DESCRIPTION: Turquoise, druzy crystals of Quartz with green patches of Chrysocolla in the matrix.
PHYSICAL CHARACTERISTICS (Quartz):
Color is as variable as the spectrum, but clear quartz is by far the most common color followed by white or cloudy (milky quartz). Purple (Amethyst), pink (Rose Quartz), gray or brown to black (Smoky Quartz) are also common. Cryptocrystalline varieties can be multicolored.
Luster is glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous.
Transparency: Crystals are transparent to translucent, cryptocrystalline forms can be translucent or opaque.
Crystal System is trigonal; 3 2.
Crystal Habits are again widely variable but the most common habit is hexagonal prisms terminated with a six sided pyramid (actually two rhombohedrons). Three of the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms (crystal lined rock with just the pyramids showing) are also common. Massive forms can be just about any type but common forms include botryoidal, globular, stalactitic, crusts of agate such as lining the interior of a geode and many many more.
Cleavage is very weak in three directions (rhombohedral).
Fracture is conchoidal.
Hardness is 7, less in cryptocrystalline forms.
Specific Gravity is 2.65 or less if cryptocrystalline. (average)
Streak is white.
Best Field Indicators are first the fact that it is very common (always assume transparent clear crystals may be quartz), crystal habit, hardness, striations, good conchoidal fracture and lack of good cleavage.
Common Name: Chrysocolla
Chemistry: CuSiO3 - nH2 O, Hydrated copper silicate
Class: Silicates
PHYSICAL CHARACTERISTICS: (Chrysocolla)
Color is a unique green-blue but can vary widely from more blue to more green, often in the same specimen.
Luster is earthy to dull or vitreous and waxy.
Transparency specimens are translucent to opaque.
Crystal System is probably monoclinic or orthorhombic.
Growth Habits include mostly massive forms that can be crusts, stalachtites and botryoidal. Also as inclusions in other minerals such as quartz.
Cleavage is absent.
Fracture is pronounced conchoidal.
Hardness is variable from 2 to 4.
Specific Gravity is approximately 2.0 - 2.3 (very light)
Streak is white to blue-green.
Best Field Indicators are lack of crystals, color, fracture, low density and softness.
Occurrence: Quartz:
Notable Occurrences of amethyst are Brazil, Uraguay, Mexico, Russia, Thunder Bay area of Canada, and some locallities in the USA. For Smoky Quartz; Brazil, Colorado, Scotland, Swiss Alps among many others. Rose Quartz is also wide spread but large quantities come from brazil as do the only large find of Rose Quartz prisms. Natural citrine is found with many amethyst deposits but in very rare quantities. Fine examples of Rock crystal come from Brazil (again), Arkansas, many localities in Africa, etc. Fine Agates are found in, of course, Brazil, Lake Superior region, Montana, Mexico and Germany.
Chrysocolla:
Notable Occurrences include Arizona, Utah, New Mexico and Pennsylvania, USA; Isreal; Zaire and England.
Rock Type: Sedimentary
Variety: Quartz:
Amethyst is the purple gemstone variety.
Citrine is a yellow to orange gemstone variety that is rare in nature but is often created by heating Amethyst.
Milky Quartz is the cloudy white variety.
Prasiolite is a leek-green gemstone variety that is rare in nature but is created by heating Amethyst from certain locations.
Rock crystal is the clear variety that is also used as a gemstone.
Rose quartz is a pink to reddish pink variety.
Smoky quartz is the brown to gray variety.
Chrysocolla:
Chrysocolla is attractive blue-green that provides a unique color to the mineral world. Chyrsocolla is perhaps more appropriately a mineraloid than a true mineral. Most of the time it is amorphous meaning that it does not have a coherent crystalline structure. However at higher temperatures it does demonstrate a distorted crystal structure that seems to be composed of Si4 O10 sheets. Chrysocolla forms in the oxidation zones of copper rich ore bodies.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
4-1/2 inDepth
4 inLength
6 inLocation
Location
Display Case
FS-16Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Jillian Mather KettleyDate
January 28, 2025Notes
Location/ inventoryLocation
Display Case
FS-4-ARoom
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 4, 2024
