Monday, March 30, 2015

Sunday, March 22, 2015

March Hachita field trip photos

Submitted by club member Andy Anderson.   Read more about this destination at this 2012 Advice to a Reader.

There is more information in this 2010 Post about Old Hachita.  

Ansel and friend picking up slag from a slag dump

Up a steep embankment

This was a really steep climb out of an arroyo

Old mine shaft and dump gathering specimens

Area around Old Hachita.

Friday, March 13, 2015

New Field Trip Report

Field Trip February 21, 2015
Submitted by Sydney Tuffly - Club Member

Stop 1 - Gravel Deposits East of Hatch, New Mexico

These gravel deposits composed of well rounded cobbles and pebbles represent Quaternary (beginning about 1.8 million years ago) age alluvial (water-laid) gravel deposits interbedded with fluvial (river-laid) gravel deposits of the Rio Grande river valley. These gravels vary in composition having been derived from igneous, metamorphic and sedimentary rocks that represent the geology of the local mountain ranges and geological terranes (fault –bounded area).

The pebbles also appear to have been polished and abraded by the erosive action of blowing sand particles giving them a high luster. Some of the pebbles and cobbles are not rounded but have a triangular shape. These wind polished rocks are called ventifacts. The triangular shape represents the three prevailing wind directions in this location.

Stop 2 – Barite Mine in the Caballos Mountains -Northeast of Hatch, New Mexico

This abandoned mining area located in the southern Caballos Mountains is in the Rincon District. It was discovered in the early 1900’s. The deposits are thin and are uneconomic. Barite has a high specific gravity (around 4.5) and is used in petroleum drilling muds, paints and paper fillers. (McLemore, 1998)

The barite-fluorite deposit in this area represents a specific type of mineral deposit called a Rio Grande rift (RGR) deposit. It is characterized by low temperature formation  as an open-space filling with no obvious connection with magma or volcanic activity. The deposit probably occurs along a fault, fractured bedding plane and/or a solution cavity in Paleozoic (251-542 mya) limestones. The deposit predominately consists of barite, fluorite, and calcite with trace accessory minerals such as, Manganese (Mn ) oxides, Iron ( Fe) Oxides, quartz, and galena . Jasperoids and banded travertine is also common. (McLemore and Giordano, 1998)

The barite in this area occurs mostly as massive fine-grained crystalline deposits but can also form the beautiful bladed box work patterns associated with barite.

The quartz crystals at this mine are excellent for collecting where large cavities, veins, and vugs are lined with drusy quartz crystals and calcite.

Also outcropping near the mine are Paleozoic limestones and interbedded siltstones containing abundant fossils. Some of the fossils included brachiopods, bryozoans, sponges, corals and foraminiferans (rice-grains).

McLemore,V.T., 1998, A Summary of the Mineral Resources in Dona Ana County, New Mexico, New Mexico Geological Guidebook, 49th Field Conference, Las Cruces County II, 1998, p. 299-308.

McLemore, V.T., Giordano, T.H., Lueth, V.W. and , Witcher ,J.C., 1998, Origin of Barite-Fluorite-Galena deposits in the Southern Rio Grande Rift, New Mexico, New Mexico Geological Guidebook, 49th Field Conference, Las Cruces County II, 1998, p. 251-264.

The location is at latitude 32degrees44'55.77"N longitude 10 degrees 7'38.29"W. This location is is north east of Hatch, NM. Exit 41east 0ff I25. Taking the left or north dirt road.

Monday, March 2, 2015

The March Beacon

Here's our newsletter for March of 2015. 
Be sure to check it out.