Monazite is one of the rare earth carbonate minerals. In fact, what we know as Monazite is technically three different minerals, but because of a lack of any significant differences between them they are referred to as one mineral. Monazite-(La) ((La, Ce, Nd)PO4) is greatly enriched in lanthanum, Mozanite-(Ce) ((Ce, La, Nd, Th, Y)PO4) in cerium and Monazite-(Nd) ((Nd, La, Ce)PO4) in neodymium. Mozanite-(Ce) is by far the most common and any sample labelled Monazite will generally be this variant.
Monazite is a primary ore of several rare earth metals most notably thorium, cerium and lanthanum. All these metals have various industrial uses and are considered quite valuable. Thorium is a highly radioactive metal and could be used as a replacement for uranium in nuclear power generation. Monazite is thus an extremely important ore mineral.
The name monazite comes from a Greek word, "monazeis", which means "to be alone", an allusion to the mineral's isolated crystals and their rarity when first discovered.
- Empirical Formula: Ce0.5La0.25Nd0.2Th0.05(PO4)
- Color is yellow to brown or orange-brown.
- Luster is vitreous, resinous or adamantine.
- Transparency: Specimens are translucent to opaque, but small crystals can be transparent.
- Crystal System is monoclinic
- Cleavage is perfect in one direction, poor in several other directions. The result is often shards or acutely angled splinters.
- Fracture is uneven but gradationally converts to conchoidal with metamictation.
- Hardness is variable from 5 - 5.5
- Specific Gravity is approximately 4.6 - 5.7 (heavy for translucent minerals)