<![CDATA[1A Collections]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/browse?sort_field=added&page=20&sort_dir=a&output=rss2 Tue, 09 Apr 2024 21:25:29 +0100 p1acollections@esc.cam.ac.uk (1A Collections) Zend_Feed http://blogs.law.harvard.edu/tech/rss <![CDATA[Fissility]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/196

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.
]]> Fri, 21 Jun 2019 15:52:17 +0100 <![CDATA[Flow banding]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/197

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.
]]> Fri, 21 Jun 2019 15:52:40 +0100 <![CDATA[Foliation]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/198

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).
foliation_1.png
foliation_2.png
]]> Fri, 21 Jun 2019 15:53:27 +0100 <![CDATA[Form]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/199

Title

Form

Description

See habit.
]]> Fri, 21 Jun 2019 15:57:59 +0100 <![CDATA[Glass]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/200

Title

Glass

Subject

When magma is quenched (cooled exceedingly rapidly) even very small crystals are unable to grow. Instead, a volcanic glass is formed. It is amorphous (having no crystalline structure), and is consequently isotropic.

Description

Have a look at the rhyolite glass (L113) in the 1A Reference Series.
]]> Fri, 21 Jun 2019 15:59:39 +0100 <![CDATA[Glomerocryst]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/201

Title

Glomerocryst

Subject

A glomerocryst is a clump of phenocrysts. A rock in which clumping of phenocrysts is abundant and pervasive is said to have a glomeroporphyritic texture.
]]> Fri, 21 Jun 2019 16:01:11 +0100 <![CDATA[Glomeroporphyritic]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/202

Title

Glomeroporphyritic

Subject

This is an igneous texture in which phenocrysts clump together, within a fine-grained groundmass.
]]> Fri, 21 Jun 2019 16:01:34 +0100 <![CDATA[Granular (or phaneritic)]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/203

Title

Granular (or phaneritic)

Subject

This texture refers to an igneous or metamorphic rock which consists entirely of interlocking, roughly equant grains, large enough to be seen with naked eye.

Description

Have a look at the hornblende biotite granite (L102) in the 1A Reference Series.
]]> Fri, 21 Jun 2019 16:05:03 +0100 <![CDATA[Graphic texture]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/204

Title

Graphic texture

Subject

The regular intergrowth of two minerals (usually quartz and feldspar), which crystallised simultaneously. It is called “graphic” because the intergrowths resemble writing.
graphic_1.png
]]> Fri, 21 Jun 2019 16:06:25 +0100 <![CDATA[Groundmass]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/205

Title

Groundmass

Subject

Rapidly cooled magmas are largely made-up of many tiny crystals. These make up the groundmass.
]]> Fri, 21 Jun 2019 16:06:53 +0100