The term “blue stone” refers to a diverse array of natural materials exhibiting blue hues. This informal description encompasses stones prized for their beauty in jewelry, geological significance, or utility in construction. Its specific meaning often depends on the context, reflecting its broad application.
Prominent Blue Gemstones
Blue gemstones are highly sought after for their aesthetic appeal and use in jewelry. Sapphire, a variety of the mineral corundum, is recognized for its deep blue color and is considered one of the most valuable blue gemstones. It ranks as the third hardest mineral after diamond, making it highly durable. Blue topaz is another popular choice, often enhanced to produce vivid shades like Swiss Blue and London Blue. This silicate mineral frequently appears in rings, pendants, and earrings.
Lapis lazuli, an opaque gemstone, is known for its intense deep blue color, often accented with golden flecks of pyrite. Ancient civilizations, including the Egyptians, revered lapis lazuli, using it in jewelry, amulets, and as pigment for art. Turquoise displays a unique robin’s egg blue to greenish-blue color and holds significant historical and cultural importance. This opaque stone has been used for its distinct color and ornamental value. Aquamarine, a member of the beryl family, presents a clear, often pale blue to blue-green shade. Its serene color makes it a favored gem for jewelry designs.
Other Notable Blue Minerals
Beyond traditional gemstones, several other blue minerals are recognized for their distinct characteristics. Azurite, a copper carbonate mineral, is known for its deep “azure” blue color. It often forms alongside malachite and has historically been used as a pigment for paints. Sodalite typically exhibits an opaque, mottled blue appearance, often with white veins. This mineral is frequently used in carvings and less expensive jewelry, valued for its unique pattern.
Kyanite is identified by its characteristic blue color and often forms in blade-like crystals. While sometimes cut as a gemstone, kyanite is more commonly used in industrial applications, such as ceramics and heat-resistant materials, due to its ability to withstand high temperatures. Dumortierite is typically found in deep blue to violet-blue shades, often occurring within quartz. This aluminum borosilicate mineral is used in ornamental objects and high-grade ceramics, recognized for its durability.
“Bluestone” as a Term for Building Materials
In construction and landscaping, “bluestone” refers to specific types of rock rather than individual minerals or gemstones. This term is commercial or regional, not a precise geological classification. It commonly designates certain sandstones or basalts that possess a characteristic blue-gray hue.
For instance, Pennsylvania bluestone is a dense sandstone quarried in the northeastern United States, known for its durability and resistance to weather conditions. This type of bluestone is widely used for patios, walkways, steps, and wall veneers, offering a natural aesthetic. Its color can vary from silvery blue to combinations of rust, tan, green, and lilac, depending on mineral deposits.
Victorian bluestone in Australia, on the other hand, is primarily a basalt, a hard volcanic rock prized for its strength and density in paving and building. These materials are selected for their structural properties and color, providing long-lasting and visually appealing surfaces for various architectural and outdoor projects.