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.
Long Beach, California Geology & Hydrogeology This post summarizes the geology of Long Beach, California. However, 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 refer to the comments function below. Ultimately, all post…
Methane on Mars Geologists understand that methane on Mars could relate to possible signs of past life, future sustainability, and similar geological processes to Earth. And sources of methane gas in the Mars atmosphere are presumably from biogenic and petrogenic processes. For example, microbial and thermal decomposition of underground organic matter, or tectonic and volcanic…
Agate Types & Geological Properties of the Agate Crystal The agate crystal is a microcrystalline-quartz mineraloid that has a lustrous display of multi-color banding and results from long-term accumulations of siliceous groundwater deposits in rock cavities. Much like other mineraloids, all agate types form over thousands of years inside the existing voids of other igneous,…
Fire Opal Gemstone – Geology & Mineralogy Information Fire Opal is an amorphous mineraloid comprising an accumulation of tiny hydrated silica spheres that produce a dominant reddish-orange spectrum upon light reflection. Although it is commonly misclassified as a “mineral,” fire opal is actually not a mineral because it does not have its own crystalline structure….
Geologic Time Scale The Geologic Time Scale is an international system used by geologists to classify and identify major geologic events and formations. The geologic timescale essentially categories the earth’s entire geologic (and biologic) history, within a series of defined eons, eras, periods, epochs, and ages. Updates & Maintenance The geologic time scale is continuously…
Geology of East Hollywood, Los Angeles, California & Hydrogeology This post summarizes the basic geology of the East Hollywood region of 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 refer…
