DALLAS, TX.- An enormous, 40-ounce gold nugget, nicknamed “Lightning Bolt” for its jolting, bright yellow glow and rarity beyond any diamond found on Earth, could take top lot honors in in Heritage Auctions’ Nature & Science Auction Aug. 18. The 11-inch nugget was discovered in Victoria, Australia, and experts have deemed the remarkable find a museum-quality specimen.

Weighing 39.9 troy ounces (43.8 ounces, or 1,241 grams), the “Lightning Bolt” (estimate: $70,000-100,000) is an absolute rarity, because of its size and aesthetic appearance, said Craig Kissick, Heritage Auctions’ Nature & Science Director.

“Gold is universal. It has been for centuries, and the demand for Gold will remain, or even increase, for generations to come. The fact that the vast majority of all Gold produced has been melted down for its pure content makes a nugget like this one even more impressive. Nuggets like this are far more rare than diamonds.”

Gold has been prized for centuries by people who see it as a standard of value and/or wealth, or simply as a measure of status. It is so rare that it has been estimated that all of the Gold ever mined on the planet would fit into a cube measuring 20 meters along each edge.

A set of five Tourmaline crystals from Paprok (Papruk Mine; Paprowk Mine) in the Kamdesh District, Nuristan Province in Afghanistan (estimate: $30,000-50,000) is a spectacular group from Paprok, a known source for exceptional specimens. Presented in matte sterling silver bases, this quintet of slender crystals offers vivid color, superb luster and excellent terminations, with each pillar – they range in height from 3-5 inches – exhibiting sidecar clusters of other minerals. The crystals are so aesthetically appealing that they can be displayed as a group or individually.

A complex cluster of minerals makes up an Azurite & Tarnowitzite from the Tsumeb Mine in Tsumeb, Oshikoto Region (Otjikoto Region), Namibia, which carries an estimate of $20,000-30,000 – figures that very well could prove to be conservative. Featuring Azurite, Calcite and Smithsonite, as well as massive clouds of Tarnowitzite, this piece is from the world-renowned Tsumeb Mine in Namibia.

As one of the “big three” gemstones, this 7.44-carat Sapphire from Myanmar (estimate: $20,000-30,000) grabs the attention of collectors immediately. Cut in a cushion shape with a modified brilliant-cut crown and step-cut pavilion, the stone is unheated and GIA-certified. The blue color includes areas of violet.

Another Gold Nugget from Victoria, Australia (estimate: $20,000-30,000) is remarkable in both its beautiful appearance and its size (12.3 troy ounces, or 13.5 ounces or 382.7 grams). The nugget displays a duality of tone as a “skin” of yellow covers the mass of Gold in certain areas, giving the impression of a layered effect.

The size, alone, of a 36.04-carat Imperial Topaz from Brazil (estimate: $20,000-30,000) is enough to demand immediate attention, but this oval-shaped stone also boasts a rich, golden honey color that is saturated and exhibits areas of darker orange. The brilliant cut allows it to light up and present an abundance of scintillation.

From the “Ross C. Lillie Collection of Illinois Minerals” comes this Fluorite from Minerva No. 1 Mine in the Cave-in-Rock Sub-District of Hardin County in Illinois (estimate: $20,000-30,000). Weighing 4.4 pounds (2 kilograms) and measuring 6 inches across the face, this specimen of well-formed cubes features rich colors, striking phantoms inside the major crystals and excellent luster over the rather clear Fluorite cubes.

Other top lots include, but are not limited to:

· Fossil Palm Frond – Green River Formation – Wyoming: $20,000-25,000

· Seymchan Meteorite End Cut – Magadanskaya Oblast, Russia: $10,000-15,000

· Megalodon Shark Tooth – Pliocene – Lower Yorktown Formation – Lee Creek Mine, Aurora, North Carolina: $5,000-7,000