Massive gray Chalcedony with brown hues.
Chalcedony, traditionally considered a variety of quartz, more recently it has been seen that it is actually a mixture of quartz with moganite, a mineral with the same chemical formula but monoclinic, the mixture producing the typical banding of some varieties of chalcedony.
It is a mineral related to quartz, with which it shares the same chemical formula; however, chalcedony is a microcrystalline variety, so it does not form well-developed crystals, they are usually tiny, so small that they are imperceptible.
The chalcedony that has the most gemological value is blue, since it is usually used in jewelry. The best stones for these works come from deposits located in Namibia.
Today it is common to find blue chalcedony gems that are actually cuts of common or grayish chalcedony and have been manipulated and dyed to achieve imitation.
The mineral includes a label with the name and origin and is attached to a cardboard box. 4 cm square.
*The price is per unit (a single cardboard box of the four shown in the photo)
Since the minerals are natural, you will receive a piece similar to the one in the photograph. The minerals come in cardboard boxes and are glued to a porex base with hot silicone; these can be removed using ethyl alcohol without damaging the mineral. The size is approximate.