Exceptional Diana Maria, The Hidden Forest Pocket Fluorite Specimen

The Specimen:

Simply an amazing example of Hidden Forest from the Diana Maria Mine in Frosterly Weardale, CO. Durham, England.

This specimen is full of crisp cubes, twins, and oh so lucid! This specimen changes from forest green to deep deep blues in natural daylight.

Size: Approximately 6.5 cm x 5 cm x 2.5 cm, 116 grams

The Mineral: Color Changing Fluorite 

Color-changing fluorite, also known as "daylight fluorite," is a type of fluorite mineral that exhibits a unique optical phenomenon in which its color appears to change when viewed under different lighting conditions. When viewed indoors or under artificial light, the fluorite may appear one color, but when viewed in natural sunlight, it may appear a different color.

The color change is caused by the presence of trace amounts of rare earth elements, such as yttrium, europium, or cerium, within the fluorite crystal lattice. These elements can absorb certain wavelengths of light and emit others, causing the apparent color of the fluorite to shift depending on the lighting conditions.

Under artificial light, the rare earth elements absorb some of the blue wavelengths of light, causing the fluorite to appear yellow or green. However, when exposed to natural sunlight, the rare earth elements absorb some of the ultraviolet (UV) wavelengths of light, causing the fluorite to emit a bluish-purple color.

It is important to note that not all color-changing fluorite exhibits the same color change. The specific color change depends on the type and amount of rare earth elements present in the crystal, as well as other factors such as the crystal's shape and orientation.

The Locality: Diana Marie

The Diana Marie Mine is located in the village of South Hetton in County Durham, in the northeast of England. The Diana Marie Mine in County Durham, England, is a former coal mine that was in operation from the mid-20th century until its closure in the early 1980s. The mine was opened in the mid-20th century and was named after the daughters of two senior NCB officials: Diana, the daughter of Sir Derek Ezra, and Marie, the daughter of Lord Robens.

The Diana Marie Mine was a drift mine, meaning that it had a sloping entryway rather than a vertical shaft. Today, the site of the Diana Marie Mine is largely reclaimed and has been repurposed for various other uses, including agriculture and nature conservation.