Bulbs
Flower Basics
Flower Beds & Specialty Gardens
Flower Garden
Garden Furniture
Garden Gnomes
Garden Seeds
Garden Sheds
Garden Statues
Garden Tools & Supplies
Gardening Basics
Green & Organic
Groundcovers & Vines
Growing Annuals
Growing Basil
Growing Beans
Growing Berries
Growing Blueberries
Growing Cactus
Growing Corn
Growing Cotton
Growing Edibles
Growing Flowers
Growing Garlic
Growing Grapes
Growing Grass
Growing Herbs
Growing Jasmine
Growing Mint
Growing Mushrooms
Orchids
Growing Peanuts
Growing Perennials
Growing Plants
Growing Rosemary
Growing Roses
Growing Strawberries
Growing Sunflowers
Growing Thyme
Growing Tomatoes
Growing Tulips
Growing Vegetables
Herb Basics
Herb Garden
Indoor Growing
Landscaping Basics
Landscaping Patios
Landscaping Plants
Landscaping Shrubs
Landscaping Trees
Landscaping Walks & Pathways
Lawn Basics
Lawn Maintenance
Lawn Mowers
Lawn Ornaments
Lawn Planting
Lawn Tools
Outdoor Growing
Overall Landscape Planning
Pests, Weeds & Problems
Plant Basics
Rock Garden
Rose Garden
Shrubs
Soil
Specialty Gardens
Trees
Vegetable Garden
Yard Maintenance
What Is the Hardest Stone?
What Is the Hardest Stone?. Diamonds are valued around the world for their beauty, sparkle and shine, but they are important for another reason as well. Diamonds are the hardest mineral on the planet, making them useful for many industrial purposes. Besides looking beautiful on her finger, a girl's best friend can also drill into the earth as well...
Diamonds are valued around the world for their beauty, sparkle and shine, but they are important for another reason as well. Diamonds are the hardest mineral on the planet, making them useful for many industrial purposes. Besides looking beautiful on her finger, a girl's best friend can also drill into the earth as well as help build cars, airplanes and engines.
General Information
According to the United States Geological Survey, diamonds are the strongest and hardest known material in the world, scoring a maximum of 10 on the Mohs Hardness Scale. They are made of pure carbon. Because of their hardness, diamonds are also the longest-lasting of all gemstones, according to Mark Helper from the University of Texas. Diamonds do not dissolve in acid, but they can be destroyed if subjected to intense heat. When a diamond is heated above 1,100 degrees Fahrenheit in the presence of oxygen, it will burn and form carbon dioxide. If it is heated to about 1,300 degrees without oxygen, it becomes graphite.
Uses
Diamonds' hardness allows them to be used for several purposes besides making jewelry. Diamonds that do not meet gem-quality standards for color, clarity, size or shape are called "industrial diamonds." These are used to cut, grind and bore other hard materials, such as metals used to make cars, airplanes and other machinery. These diamonds are also placed on the end of mining drills. Diamonds can only be cut by other diamonds, but they can be cleanly broken with a sharp, accurate blow because of their cleavage. Cleavage is the property that allows some stones to split in certain directions and produce flat surfaces. Diamond cutters have been using iron wheels coated with diamond dust to shape and polish stones to make jewelry since the 1400s, according to Helper.
Why Are Diamonds So Hard?
Diamonds are extremely hard because of the tremendous chemical bond between each carbon atom. Moreover, the atoms in diamonds form a rigid structure, such that each atom is connected to four others, creating a regular and sturdy network that is almost indestructible.
Other Hard Stones
According to the American Federation of Mineralogical Societies, corundum is the world's second hardest stone, scoring a 9 on the Mohs Hardness Scale. It is 25 percent as strong as a diamond. The transparent varieties of corundum include rubies and sapphires. Nontransparent corundum is used to grind, smooth and polish other hard materials. Topaz, scoring an 8 on the Mohs Hardness Scale, is the world's third hardest stone. Emerald and aquamarine are common varieties of topaz, which is half as hard as corundum.
