URGENT MESSAGE: We need $75,000 to survive. Click here to find out why.
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for Educators
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Quartz-beta

This page is currently not sponsored. Click here to sponsor this page.
Formula:
SiO2
Specific Gravity:
2.5334 (Calculated)
Crystal System:
Hexagonal
Dimorph of:
A high-temperature (> ~573°C) polymorph of silica with a crystal structure very similar to that of quartz, but with a higher symmetry (beta-quartz: hexagonal, quartz: trigonal; Bragg and Gibbs, 1925; Heaney, 1994). Like quartz, beta-quartz occurs in left- and right-handed crystals.

Unstable at room temperature, it cannot be quenched from high temperatures. All "beta-quartz" or "quartz-beta" or "high quartz" in collections actually represent paramorphs of quartz after beta-quartz. This is why on Mindat there's not a single photo labeled "quartz-beta", they are all labeled quartz.

The phase transition is at about 573°C at ambient pressures. When heated quickly, beta-quartz melts at about 1550°C, otherwise it will turn into beta-cristobalite at around 1050°C. The temperature of the phase transition from quartz to beta-quartz increases with pressure.

Quartz pseudomorph after beta-quartz in rhyolite matrix
Quartz paramorph after beta-quartz grown in a cavity
Quartz pseudomorph after beta-quartz in rhyolite matrix
Quartz paramorph after beta-quartz grown in a cavity
Quartz pseudomorph after beta-quartz in rhyolite matrix
Quartz paramorph after beta-quartz grown in a cavity

Beta-quartz is most commonly found in silica-rich volcanic rocks like rhyolite, in which it occurs as stubby, bipyramidal and usually dull and gray crystals embedded in the matrix. This has led people to believe that quartz crystals with a bipyramidal habit grew as beta-quartz, and the habit is unfortunately called "beta-type" or similar.

However, beta-quartz that grows freely in cavities frequently forms elongated crystals that are very similar to quartz, or even as very thin, needle-like crystals Eg: https://www.mindat.org/photo-214061.html.










Hide all sections | Show all sections

Physical Properties of Quartz-betaHide

Density:
2.5334 g/cm3 (Calculated)

Chemical Properties of Quartz-betaHide

Formula:
SiO2

Crystallography of Quartz-betaHide

Crystal System:
Hexagonal
Class (H-M):
6 2 2 - Trapezohedral
Space Group:
P64 2 2
Cell Parameters:
a = 4.9977 Å, c = 5.4601 Å
Ratio:
a:c = 1 : 1.093
Unit Cell V:
118.11 ų (Calculated from Unit Cell)

Synonyms of Quartz-betaHide

Other Language Names for Quartz-betaHide

German:Hochquarz

Common AssociatesHide

Associated Minerals Based on Photo Data:
Calcite5 photos of Quartz-beta associated with Calcite on mindat.org.
Plume Agate1 photo of Quartz-beta associated with Plume Agate on mindat.org.
Iris Agate1 photo of Quartz-beta associated with Iris Agate on mindat.org.
δ-Quartz1 photo of Quartz-beta associated with δ-Quartz on mindat.org.
1 photo of Quartz-beta associated with on mindat.org.
Aegirine1 photo of Quartz-beta associated with Aegirine on mindat.org.
Quartz1 photo of Quartz-beta associated with Quartz on mindat.org.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Quartz-betaHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Drugman, J. (1911) An example of quartz twinned on the primary rhombohedron. Mineralogical Magazine: 16: 112-117.
Bragg, W., Gibbs, R.E. (1925) The structure of α and β quartz. Proceedings of the Royal Society of London, Series A: 109(751) 405-427.
Heaney, P.J. (1994) Structure and chemistry of the low-pressure silica polymorphs. In: Reviews in Mineralogy, Volume 29, Silica - Physical behavior, geochemistry and materials applications. Mineralogical Society of America, Washington, D.C.

Internet Links for Quartz-betaHide

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: June 23, 2018 09:31:33 Page generated: June 16, 2018 14:02:50
View slideshow - Go to top of page