Mineral Of The Day

Mineral Of The Day #133: Tiger’s Eye

Mohs Hardness Scale: 7
Category: silicate mineral, quartz group
Formula: SiO₂

Fun Facts:

• Tiger’s eye is a chatoyant gemstone (which means it has an optical reflectance effect as a result of the fibrous structure of the material).
• It occurs when silica replaces crocidolite.
• Tiger’s eye is the anniversary gemstone symbolizing the 9th year of marriage.
• Roman soldiers wore tiger’s eye for protection in battle!

Mineral Of The Day #125: Marcasite

Mohs Hardness Scale: 6-6.5
Category: sulfide mineral
Formula: FeS₂

Fun Facts:

• Marcasite is a polymorph of pyrite (meaning it has the same chemical formula as pyrite, but a different crystal structure).
• The most famous habit for marcasite is the “cock’s comb” twinned habit. The crystals appear like a rooster’s head crest, hence the name.
• It is used as a minor ore of iron, a source of sulfur, and as mineral specimens.
• “Marcasite jewelry” is actually made from pyrite, not marcasite!

Mineral Of The Day #119: Gold

Mohs Hardness Scale: 2.5
Category: Native element

Formula: _Au

Fun Facts:

• Spinning straw into gold for three consecutive nights makes a woman eligible to marry a king.
• There is a pot of it at the end of every rainbow.
• Everything that King Midas touched turned to gold.
• Alchemy is the process by which copper and other base metals are turned to gold by way of an elixir.
• Medically, gold is used in dentistry, and it makes an attractive gold tooth.

APRIL FOOLS!

Mineral Of The Day #119: Pyrite

Mohs Hardness Scale: 6-6.5
Category: Sulfide mineral

Formula: FeS₂

Fun Facts:

• Pyrite is also known as “Fool’s Gold” because of its resemblance to gold.
• It is the most common sulfide mineral.
• It was used in the 16th and 17th centuries as a source of ignition in early firearms.
• Commercially, it is used for the production of sulfur dioxide, which is used in the paper industry.
• Pyrite is also used to make marcasite jewelry.