Hedenbergite
The iron-rich calcium pyroxene, which grew in carbonaceous chondrites as fluids altered the rock.
Key facts
- Formula
- CaFeSi2O6
- Family
- Silicates
- Crystal system
- Monoclinic
What it is
Hedenbergite is the iron end of the diopside–hedenbergite series, a high-calcium pyroxene in which iron replaces magnesium. It is named after Ludwig Hedenberg, an early Swedish chemist.
Where it is found
In CV chondrites such as Allende, hedenbergite forms with andradite garnet, fayalite and wollastonite in veins and rims around CAIs and chondrules. These minerals grew when warm, salty fluids reacted with the rock inside the parent asteroid. It is also found in a few angrites and in highly evolved lunar basalts.
How it is recognised
It is dark green to black. In meteorites it is usually fine-grained and identified by its chemistry with an electron microprobe, together with the minerals that grow with it.
Did you know?
The same set of minerals, hedenbergite with andradite, forms in Earth's skarns, where hot fluids react with limestone.
Its presence in Allende shows that even this famous primitive meteorite was touched by water.