This is a 1.3" wide association of yellow-green diopside crystals and andradite garnets. This mineral association was collected from Khogyani, Afghanistan
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.
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).