THE
MINERAL MOCTEZUMITE
- Chemistry:Pb(UO2)(TeO3)2,
Lead Uranyl Tellurite
- Class: Sulfates
- Subclass: Tellurites
- Uses: Only as mineral specimens.
- Specimens
Moctezumite is a very rare tellurium mineral discovered in 1965 by Richard Gaines (1917 - 1999), an American minerologist.
Its type locality is the Moctezuma Mine, Moctezuma, Sonora,
Mexico, hence the name.
The Moctezuma Mine is famous for rare telllurium minerals.
Other minerals from here include:
bambollaite,
cliffordite,
denningite,
emmonsite,
spiroffite,
tellurium and
zemannite.
Not only is moctezumite a tellurium mineral, it is also a uranium mineral.
The uranium ion in moctezumite is part of a group of ions called the uranyl ion group.
The uranyl ion group,
UO2, is unusual in that it is a positively charged (
+2) ion group.
Most ionic groups, especially those that contain oxygen are negatively charged such as
the sulfate ion group,
SO4-2;
carbonate ion group,
CO3-2;
borate ion group,
BO3-3;
phosphate ion group,
PO4-3;
tellurite ion group,
TeO3-2 and
the silicate ion group,
SiO4-4.
Another positively charged ion group is the ammonium ion group,
NH4+1, found in only a few minerals.
Remember, moctezumite is a radioactive mineral and should be stored away from minerals that are affected by radioactivity and of course human exposure should be limited.
THE PHYSICAL CHARACTERISTICS:
- Color is orange to brownish orange.
- Luster is vitreous to adamantine.
- Transparency: Crystals are translucent.
- Crystal System is monoclinic; 2/m.
- Crystal Habits include small granular crystals.
- Cleavage is good in one direction.
- Hardness is 3.
- Specific Gravity is approximately 5.7 (very heavy for translucent
minerals).
- Streak is pale orange.
- Other Characteristics: Specimens are radioactive and index of refraction is very high at
2.11 to 2.12.
- Associated Minerals include various other tellurium minerals such
bambollaite,
cliffordite,
denningite,
emmonsite,
spiroffite,
tellurium,
zemannite
and other
tellurates and tellurites.
- Notable Occurrences are limited to the type locality of Moctezuma Mine, Moctezuma, Sonora,
Mexico.
- Best Field Indicators are locality, high density, color, radioactivity and cleavage.
