Corundum Crystal, North Carolina

Description

Corundum, Franklin, Canton & Hickory North Carolina

 Corundum (Sapphire & Ruby) crystals in various colors, including red, pink and deep blue. These colors are often all mixed in the same crystal. The specimens found here often are hexagonal form with flat basal pinacoid terminations and textured surfaces composed of many microscopic crystal faces which are beautiful when magnified under light. Corundum was first discovered here as loose crystals in plowed fields and gardens.When the Propst family stopped farming the land, they began to allow rock hounds to access the fields and adjacent forest to collect for a small fee. Even after Mrs. Propst, became a widow she continued to allow rock hounding on her property. Due to an incident with an individual rockhound club member she banned that individual and also all clubs for a while. She did not like having large groups show up all at once. Mrs. Propst finally allowed individuals and small groups to access the property for a fee of $5 per person. We started going to this site in the mid 80’s and have collected their a number of times over the last twenty Plus year.The corundums are normally found between 4 and 8 feet down. You will have to remove lots of red dirt and sometimes a greyish-yellow layer close to the corundums. It is hard work and very hot and humid during most of the summer access times.

Corundum is a crystalline form of aluminium oxide (Al₂O₃) typically containing traces of iron, titanium, vanadium and chromium.^[3][4] It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure.^[7] Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present.^[7] A rare type of sapphire, padparadscha sapphire, is pink-orange.

The name “corundum” is derived from the Tamil–Dravidian word kurundam (ruby-sapphire) (appearing in Sanskrit as kuruvinda).^[8][9]

Because of corundum’s hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. It is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood. Emery, a variety of corundum with no value as a gemstone, is commonly used as an abrasive. It is a black granular form of corundum, in which the mineral is intimately mixed with magnetite, hematite, or hercynite.^[6]

In addition to its hardness, corundum has a density of 4.02 g/cm³ (251 lb/cu ft), which is unusually high for a transparent mineral composed of the low-atomic mass elements aluminium and oxygen.

North Carolina Corundum Geology and occurrences

(Clay Cleveland Macon Jackson Maddison County)   occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes. It also occurs in low-silica igneous syenite and nepheline syenite intrusives. Other occurrences are as masses adjacent to ultramafic intrusives, associated with lamprophyre dikes and as large crystals in pegmatites.^[6] It commonly occurs as a detrital mineral in stream and beach sands because of its hardness and resistance to weathering.^[6] The largest documented single crystal of corundum measured about 65 cm × 40 cm × 40 cm (26 in × 16 in × 16 in), and weighed 152 kg (335 lb).^[11] The record has since been surpassed by certain synthetic boules.^[12]