Ferruginous Quartz: Natural Red Quartz

Ferruginous Quartz

Ferruginous Quartz is a variety of quartz that is colored red by the presence of iron oxide. The iron oxide can be in the form of hematite, goethite, or limonite. Ferruginous Quartz is typically opaque, but it can sometimes be translucent or even transparent. It is often called "red quartz" or "hematoid quartz".

It is usually massive and opaque, and can be found in a variety of geological settings, including sandstone, shale, and quartzite. Ferruginous quartz is often found in association with other iron-rich minerals, such as magnetite, hematite, and limonite. It can also be found in association with other types of quartz, such as agate and jasper.

Color:

The color varies between yellow, orange, red, and brown tones of different intensities. At many locations the crystals show a patchy coloration, sometimes even with different colors in one crystal. The specimen are usually translucent to almost opaque, but never transparent.
 

Natural 'eisenkiesel' quartz cluster. Chella, Valencia, Valencian Community, Spain Photo: Carlos Pareja

Occurrence:

Ferruginous Quartz is found in many different parts of the world, including Brazil, Madagascar, Morocco, and the United States. It is often found in association with other minerals, such as agate, jasper, and calcite.

Types:

• Fire quartz: This type of ferruginous quartz is characterized by its bright red color.
• Tangerine quartz: This type of ferruginous quartz is characterized by its orange color. It is often used in jewelry and is said to promote creativity and optimism.
• Eisenkiesel: Eisenkiesel (German for "iron pebble", pronounced "i-zen-keezle"). This type of ferruginous quartz is found in Germany and is known for its yellow-brown color. It is often used in healing crystals and is said to be beneficial for the heart and blood.  
• Jacinto de Compostela is a type of ferruginous quartz that is found in Spain. Jacinto quartz is typically opaque, but it can sometimes be translucent. Jacinto quartz is found in the province of Valencia, Spain. 

Bright red hematite phantom quartz cluster, from Orange River, South Africa. Photo: The Eclectic Collects