Amethyst crystals found at the Buckskin Mining District

Recently a member of the Lake George Gem and Mineral Club took to the field to search for rocks and minerals from the Buckskin Mining District.  The District was established in 1859 when this part of Colorado was still part of Kansas Territory.  Buckskin Creek was a source of gold nuggets.  The gold played out in a few years.  Silver was later found in the upper reaches of the gulch.

This silver ore specimen contains a void that is lines with
amethyst quartz crystals. The area is noted for its silver
production.



 

Brecciated Silver Ore from the Alma District

Rounded fragments are held by a cementing matrix

One of our our study members found this unsual ore specimen that reveals brecciation.  Note the small, rounded clasts.

Breccia is a rock composed of fragments of minerals or rocks in a matrix (cementing material). The fragments in this specimen are different from the composition of the matrix. This may be a hydrothermal breccia. This type of breccia  is formed in a void along a fault underground. The void draws in hot water that violently boils--like an underground geyser. Rock at sides of the fault fall inwards and the broken rock gets caught up in a churning mixture of rock, steam and boiling water. The rock fragments hit each other and sides of the fault which quickly rounds the once angular breccia fragments.