THE MINERAL RAMSDELLITE

Chemical Formula: MnO2, Manganese Oxide.
Class: Oxides and Hydroxides
Uses: A minor ore of manganese and as a mineral specimen.
Specimens

Ramsdellite is a rather uncommon mineral to be seen in mineral markets. Partly because of its rarity, partly because of its general lack of good crystals and partly because of its difficulty in being identified. Ramsdellite is polymorphous (meaning many shapes) with the relatively common mineral pyrolusite. The two minerals have the same chemistry, but different structures. Pyrolusite is tetragonal and ramsdellite is orthorhombic. A third mineral, akhtenskite, is much more rare than these two and is also a polymorph being hexagonal. The three minerals are thus referred to as trimorphs.

Ramsdellite is an oxidation product of weathered manganese minerals, such as manganite. Ramsdellite is often a minor constituent of "Wad". The mining term "wad" is used to indicate massive ores that are a mixture of several manganese oxides such as pyrolusite, psilomelane, ramsdellite and others that are difficult to distinguish. Manganese is a strategically valuable metal since it is an essential ingredient in steel and other alloys.

PHYSICAL CHARACTERISTICS:

Color is black to gray.
Luster is metallic to dull.
Transparency: Crystals are opaque, translucent in only thin splinters.
Crystal System is orthorhombic; 2/m 2/m 2/m
Crystal Habit is typically massive and granular. Crystals are uncommon and tabular.
Cleavage is good , but rarely seen except in rare large crystals.
Fracture is conchoidal to uneven.
Hardness is approximately 3, but is variable.
Specific Gravity is 4.4 - 4.8 (average for metallic minerals)
Streak is black.
Associated Minerals are limonite, hematite, quartz, manganite, psilomelane, pyrolusite and other manganese and iron oxide minerals.
Notable Occurrences include nice specimens from Germany; former Czechoslovakia; Lake Valley, New Mexico, Minnesota, California and Montana, USA.
Best Field Indicators are habits, luster, softness, color and streak.