Common Opal is a specific type of opal that usually exists in one color, and has no play-of-color when flashed with light. Unlike precious opal, common opal appears to be “glassy” with transparent and translucent properties. A common blue opal or fire opal gemstone will predominantly reflect one pigment of color from any viewpoint. Please refer to the photograph below for an example of a common opal stone. Updated February 23, 2021.
The Black Quartz Crystal (Morion) is Actually the Smokey Quartz Gemstone The black quartz crystal is actually the same mineral as smokey quartz and morion quartz, and only differs from the common quartz mineral due to its aluminum content. In fact, aluminum is the root cause of its light-absorbing characteristic, which causes a translucent-gray to…
Is the Earth Around Millennium Tower Sinking? Is the earth around the Millennium Tower sinking? Built-in 2008, the Millennium Tower in San Francisco has reportedly sunken about 17 inches into the ground surface. This subsidence is a consequence of improper geotechnical engineering design and potential changes in the hydrogeological setting. Moreover, surveyors indicate the structure is…
The Historical Salton Sea Fishery The Salton Sea fishery is a historical part of the Salton Sea, California’s largest body of water and arguably, the largest environmental disaster to date. At a time before toxicity levels at the Salton Sea became problematic, many fish species were stocked into the lake for sport and commercial purposes….
Soil pH Test Strips The pH of soil can be measured using a variety of different devices, or pH testers, which can quickly indicate to a user the pH of their soil. Soil ph test strips determine a numerical value indicating the acidity or alkalinity of soil. The pH scale ranges from 0 to 14,…
The St. Francis Dam Disaster The St. Francis Dam disaster of 1928 was the failure of a large concrete gravity dam due to unmitigated geologic hazards, causing over 55 miles of violent flooding, and over 400 deaths. It is said to be California’s worst engineering catastrophe to date. Updated April 11, 2024. Saint Francis Dam…
Geology of the Chinatown Area in Los Angeles, California & Hydrogeology This post summarizes the geology of the Chinatown region, of Downtown Los Angeles California. Some geological and hydrogeological data may be incomplete or pending review. Nonetheless, students, geologists, and earth scientists are welcome to openly use, critique, and contribute information. To do so, please…
