<![CDATA[1A Collections]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/browse?page=27&sort_field=Dublin+Core%2CTitle&output=rss2 Tue, 09 Apr 2024 21:26:11 +0100 p1acollections@esc.cam.ac.uk (1A Collections) Zend_Feed http://blogs.law.harvard.edu/tech/rss <![CDATA[Zonation]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/267

Title

Zonation

Subject

As a crystal grows slowly in a magma chamber the magma from which it is crystallising may evolve, changing its composition. Thus later crystallising regions or “zones” of the crystal will have a slightly different composition from earlier crystallising regions. The crystal thus displays zonation.
Zonation is seen under cross-polarised light by variations in the birefringence colours of the different zones.

Description

Have a look at the granodiorite (L120) in the 1A Reference Series.
]]> Fri, 21 Jun 2019 17:59:38 +0100 <![CDATA[Chronostratigraphic Chart]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/269

Title

Chronostratigraphic Chart
ChronostratChart2019-05.pdf
]]> Thu, 04 Jul 2019 14:18:21 +0100 <![CDATA[Michel-Levy Chart]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/268

Title

Michel-Levy Chart
Michel-Levy Chart (scan).pdf
]]> Thu, 04 Jul 2019 14:09:00 +0100 <![CDATA[Pleochroism]]> https://wserv3.esc.cam.ac.uk/p1acollections/items/show/239

Title

Pleochroism

Subject

Some minerals are pleochroic. When rotated under plane polarised light they change colour. Biotite and the amphibole hornblende are pleochroic.

Description

Have a look at hornblende amphibole (M201, M211) and biotite mica (M303, M304) in the 1A Reference Series.
]]> Fri, 21 Jun 2019 17:07:27 +0100