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18 January 2015

Geology Word of the Week: J is for Jasper

def. Jasper: A dense, opaque variety of chalcedony. Jasper is most often red in color but can also be yellow, brown, green, or gray.   For this week’s Geology Word of the Week post, we’re going to learn a little about silica, aka silicon dioxide or SiO2. More specifically, we’re going to learn about silica minerals. Silicon and oxygen are the two most common elements in the Earth’s crust and are found in many, …


13 October 2014

Monday Geology Picture: A Mineral Rainbow at the Smithsonian

Minerals come in a rainbow of colors. Sometimes, mineral color is a result of the mineral’s composition. For example, azurite is always blue. Other times, mineral color is a result of small quantities of trace elements or structural defects in the mineral. For example, quartz, one of the most common minerals, is most often clear or white but can be other colors such as rose pink, yellow, purple, and even …


28 October 2012

Geology Word of the Week: Z is for Zeolite

def. zeolite: The name of a large group of porous, framework, aluminosilicate (their basic structure is interlocking tetrahedra of SiO4 and AlO4) minerals that contain significant water and also significant exchangeable cations, which makes them absorbent materials. The name zeolite originates from the Greek words “zeo”, which means “to boil”, and “lithos”, which means “stone”. Zeolites were given their name because when you heat them, they generally release water in …


28 April 2012

Geology Word of the Week: U is for Ulexite

def. Ulexite: 1. Hydrated sodium calcium borate hydroxide (formula: NaCaB5O6(OH)6•5(H2O) ), a silky, brittle, generally white evaporate mineral  which often crystallizes in the form of densely-packed fibers that transmit light along the long axis of the mineral. 2. A party trick rock. Have any party guests who think that geology isn’t awesome? Just pull out your fibrous ulexite sample and say, “Hey look, I have a fiber optic rock.” Then …