This is a gorgeous, 1.6" wide association of yellow-green diopside crystals, andradite garnets, magnetite crystals and biotite clusters. This mineral association was collected from Khogyani, Afghanistan and is in great condition. The magnetite has wonderful magnetic properties.
Diopside is a pyroxene mineral with the chemical formula MgCaSi₂O₆. It is often found as small green crystals within metamorphic and igneous rocks, though it can vary in color including yellow, brown and black crystals. It is an important indicator rock when searching for deep-source volcanic pipes that may or may not contain diamonds. Geologists that are searching for these pipes often look for diopside crystal fragments since they form in nearly the same atmospheric conditions and locations as diamonds. Diopside crystals with deep green coloration are known as chrome diopside.
Magnetite is an iron oxide mineral with the chemical formula Fe₃O₄. It the most magnetic naturally occurring mineral on earth and is an important iron ore. It has an iron content of up to 72.4% which explains why it is such a commonly mined iron ore. Magnetite can be found in igneous, metamorphic and sedimentary rock.
Andradite is a species of the Garnet group, and although not as well-known as some other types of Garnets such as Almandine or Pyrope, it is the most lustrous. It tends to be opaque, so most andradite does not make for good gemstones. It occurs in skarns developed in contact metamorphosed impure limestones or calcic igneous rocks; in chlorite schists and serpentinites and in alkalic igneous rocks (typically titaniferous).
Garnets are nesosilicates having the general formula X3Y2(Si O4)3. There are many species of garnet which are pyrope, almandine, spessartine, uvarovite, andradite and grossular (varieties of which are hessonite or cinnamon-stone and tsavorite).