Upcoming Rockhounding Events in Alabama
Marble forms when limestone or dolomite is subjected to heat and pressure caused by thick layers of overlying sediment. This metamorphism can result in impurities in the limestone recrystallizing and forming mineral impurities that impact the texture and color of the marble. Desirable, pure-white marble is formed by very pure, silicate-poor limestone or dolomite.
Marble is an economically valuable rock. It is used in everything from fine arts to construction aggregate. Different locations produce marbles of varying quality or color that can be used for different purposes.
Marble is in the Public Domain
Star Blue Quartz
Chemical Formula: SiO2
Star Blue Quartz is the state gemstone of Alabama. This variety of quartz boasts a stunning blue color due to inclusions, commonly of fibrous magnesioriebeckite or crocidolite. This variety of quartz can be found near the Flint River on the Georgia border.
Quartz is one of the most common minerals found in the Earth’s crust. While it is usually colorless and transparent, quartz can also be found in a wide variety of colors and a range of opacity. These varieties generally have their own name such as rose quartz, amethyst, smoky quartz, and citrine.
Quartz can also be found in cryptocrystalline varieties, or quartz that is made up of microscopic crystals. These varieties include chalcedony, agate, and jasper.
Streak: Cherry-red or red- brown
Hardness: 5 – 6
Chemical Formula: Fe2O3
Hematite is an abundant and vital iron ore. It can be found in a wide variety of habits from steel-gray crystals to scaly forms of micaceous hematite. Hematite can also be found in petal-like arrangements or as short, rhombohedral crystals with an iridescent tarnish. All of these varieties still share the same rust-red streak.
Hematite is also used as a pigment, lending itself to use by ancient humans for writing and social purposes. Ochre, clay containing hematite, has served as pigment throughout the years and is still mined today in France.