2.15" Gemmy Dioptase Crystals on Dolomite - Ntola Mine, Congo

This is a very nice association of dioptase crystals, dolomite and mimetite from the Ntola Mine of the Republic of Congo. The entire specimen is 2.15" wide. The dioptase crystals have a saturated, dark emerald-green color while the mimetite is vibrant orange in color and can be found mixed in with the matrix. The rock matrix is encrusted in dolomite crystals.

The dioptase cluster has been mounted to an acrylic display stand.

Dioptase is an uncommon mineral, found mostly in desert regions where it forms as a secondary mineral in the oxidized zone of copper sulfide mineral deposits. This copper-based mineral forms small rhombohedral crystals, typically less than 0.75 centimeters in length. It is popular with mineral collectors due to its vibrant color and it is occasionally cut into small emerald-like gems.

About Mimetite

Mimetite is a rare lead arsenate chloride mineral, often found in shades ranging from bright yellow to orange, brown, and occasionally green. Its crystals form in a hexagonal structure, typically appearing as prismatic or rounded barrel shapes, though they can also form in botryoidal or globular clusters. This mineral belongs to the apatite group and is closely related to pyromorphite and vanadinite, with which it can sometimes be found in mixed forms. Mimetite's vibrant colors and crystal formations make it a popular specimen among mineral collectors, as it is often highly aesthetic and eye-catching.

This mineral is usually found in the oxidized zones of lead ore deposits, commonly associated with minerals such as galena, wulfenite, and cerussite. It can be found in notable deposits worldwide, including locations in Mexico, Namibia, and Australia, where large and well-formed specimens have been unearthed. Mimetite crystals are relatively fragile due to their lead and arsenic content, requiring careful handling. Despite its appeal, mimetite is not used in jewelry or as a decorative stone because of its toxic elements, making it mainly a collector's mineral.

Dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate (CaMg(CO3)2).

The mineral dolomite crystallizes in the trigonal-rhombohedral system. It forms white, tan, gray, or pink crystals. Dolomite is a double carbonate, having an alternating structural arrangement of calcium and magnesium ions. It does not rapidly dissolve in dilute hydrochloric acid as calcite does. Crystal twinning is common.

Dolomite was first described by Carl Linnaeus in 1768, and in 1791 it was described as a rock by the French naturalist and geologist Déodat Gratet de Dolomieu. He first recognized the material in buildings of the old city of Rome, and later as samples collected in the mountains known as the Dolomite Alps of northern Italy.


SOLD
DETAILS
SPECIES
Dioptase, Mimetite & Dolomite
LOCATION
Ntola Mine, Mindoili District, Republic of Congo
SIZE
2.15 x 1.4"
CATEGORY
ITEM
#130501