https://wserv3.esc.cam.ac.uk/p1acollections/items/browse?page=8&sort_field=added&sort_dir=d&output=atom <![CDATA[1A Collections]]> 2024-04-09T21:22:26+01:00 Omeka https://wserv3.esc.cam.ac.uk/p1acollections/items/show/199 <![CDATA[<h2>Form</h2>]]> See habit.]]> 2019-07-04T09:53:07+01:00

Title

Form

Description

See habit.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/198 <![CDATA[<h2>Foliation</h2>]]> 2019-07-04T09:53:06+01:00

Title

Foliation

Subject

This refers to any pervasive planar feature in a rock. It is produced by the arrangement of the constituent grains into sheet-like structures, usually in compositionally distinct layers. Foliations can be primary (e.g. bedding, fissility, flow banding) or secondary (e.g. cleavage).
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/197 <![CDATA[<h2>Flow banding</h2>]]> 2019-07-04T09:53:06+01:00

Title

Flow banding

Subject

This occurs when an inhomogeneous magma flows, thereby drawing out the inhomogeneities into bands of different compositions. When this happens on a very fine scale it is called flow lamination.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/196 <![CDATA[<h2>Fissility</h2>]]> 2019-07-04T09:53:06+01:00

Title

Fissility

Subject

This refers to the tendency of some sedimentary rocks to break along their bedding planes. Shales are fissile. Fissility is distinct from cleavage because cleavage is not aligned with the bedding planes.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/195 <![CDATA[<h2>Fibrous</h2>]]> 2019-07-04T09:53:05+01:00

Title

Fibrous

Subject

This texture consists of a mass of fine strand-like crystals. It often occurs in igneous rocks which have undergone rapid cooling.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/194 <![CDATA[<h2>Ferromagnesian mineral</h2>]]> 2019-07-04T09:53:05+01:00

Title

Ferromagnesian mineral

Subject

A silicate mineral containing a high proportion of iron and/or magnesium. These minerals tend to be dark in colour. Common ferromagnesian minerals include olivine, pyroxenes, amphiboles, biotite mica and garnet.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/193 <![CDATA[<h2>Facetted</h2>]]> 2019-07-04T09:53:04+01:00

Title

Facetted

Subject

A facetted crystal has a number of planar surfaces called faces. These are produced during the growth of the crystal.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/192 <![CDATA[<h2>Fabric</h2>]]> 2019-07-04T09:53:04+01:00

Title

Fabric

Subject

The fabric of a rock describes the geometric arrangement of its constituent grains. The term is most commonly applied to metamorphic rocks. These may display either linear or planar fabrics, depending on the deviatoric stresses present during their formation.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/191 <![CDATA[<h2>Extrusive</h2>]]> Compare with intrusive.]]> 2019-07-04T09:53:04+01:00

Title

Extrusive

Subject

Rocks which have formed by the eruption of igneous material onto the surface of the Earth are described as extrusive.

Description

Compare with intrusive.
]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/190 <![CDATA[<h2>Extinction</h2>]]> 2019-07-04T09:53:03+01:00

Title

Extinction

Subject

As a mineral grain is rotated under cross-polarised light it will periodically turn black. When the grain is black it is in extinction. The extinction positions occur at every 90° of rotation. This position is measured in degrees from a prominent feature of the mineral grain, such as a cleavage plane or a face of a euhedral crystal.
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