An unusual cluster of Dogtooth Wulfenite crystals on matrix. Another sought after Mexican mineral for your collection! Great colour on a rustic-looking rock. You can see why many people dedicate much of their collections to this locale. Not an everyday mineral and this specimen shows a less-common crystal shape for Wulfenite. One for the collector.
La Ojuela Mine, Mapimi, Mexico.
12.5cm x 10cm x 3cm, 288g.
A secondary mineral typically thin tabular, dog tooth and other crystals. Bright orange red, yellow orange, yellow or yellow grey colors. Found in the oxidised zones of hydrothermal lead deposits. Stubby, Pyramidal crystals often tabular with a square outline.
Uses: A minor ore of molybdenum and as mineral specimens.
Wulfenite is a nice collection type mineral and is popular as such. Its strong colors, nice luster and one-of-a-kind crystal habits attract the attention of many collectors around the world.
Wulfenite is an enigma in terms of its symmetry. There are conflicting results of various symmetry tests and this usually does not happen. It is either a symmetry of 4 or 4/m. The difference is the disputed existence of a mirror plane perpendicular to the four fold axis. If the mirror exists, then the crystals should have a top that is a mirror image of its bottom. Most crystals don’t show it clearly, the bottom pyramidal faces slant at a different angle from the top pyramidal faces. This demonstrates the symmetry of just 4. However, other tests of its symmetry show a 4/m symmetry. This symmetrical oddity only adds to wulfenite’s interest among serious collectors.
Color is red, orange, yellow, silver and white.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System is tetragonal; 4/m or 4
Crystal Habits include very thin square or octahedral pinacoidal plates with pyramidal faces truncating just the edges of the crystal. At times the pyramids become prominent and pseudo dipyramidal crystal habits are seen. This is sometimes because of twinning. Prismatic faces are also seen and can make pseudo cubic crystals. Encrusting and cavernous aggregates due to inter growth of crystal plates.
Cleavage is perfect in one direction.
Fracture is conchoidal.
Hardness is 3.
Specific Gravity is approximately 6.8 (very heavy for translucent minerals)
Streak is white.
Associated Minerals are mimetite, limonite, smithsonite, vanadinite and galena.
Other Characteristics: index of refraction is 2.28-2.40 (very high, but typical of lead minerals).
Notable Occurrences include Morocco; Tsumeb, Namibia; Mexico and Arizona and New Mexico, USA.
Best Field Indicators are crystal habit, color, density and luster.