Gold

Gold is a chemical element with the symbol Au (from the Latin aurum) and atomic number 79. It is a dense, malleable, and ductile metal that has fascinated humanity since antiquity due to its lustre, rarity, and resistance to corrosion. Found naturally in its metallic state, gold has played a central role in global economics, art, and technology for thousands of years. Its enduring appeal lies in both its intrinsic beauty and its remarkable physical and chemical stability.

Physical and Chemical Properties

Gold is a transition metal belonging to Group 11 of the periodic table. It is distinguished by its bright yellow metallic sheen, excellent conductivity, and high density (19.3 g/cm³). The concentration of free electrons in gold metal is approximately 5.90 × 10²² cm⁻³, giving it exceptional electrical and thermal conductivity.
One of gold’s most remarkable properties is its resistance to oxidative corrosion and tarnish, making it one of the least reactive chemical elements. Gold does not react with oxygen or most acids, but it can be dissolved by aqua regia, a powerful mixture of concentrated nitric acid and hydrochloric acid in a ratio of 1: 3. This reaction forms chloroauric acid (HAuCl₄). Gold also reacts with alkaline cyanide solutions, forming soluble complexes used in gold extraction.
Aqua regia, meaning royal water, earned its name because it can dissolve noble metals such as gold and platinum. Despite this, metals like tantalum, titanium, osmium, and iridium resist its corrosive effects.

Measurement of Purity: Carats and Fineness

Gold purity is traditionally measured in carats (k), with 24-carat gold representing pure gold (99.9% Au by weight). The carat system expresses the fraction of pure gold present in an alloy:
X=24×MgMmX = 24 \times \frac{M_g}{M_m}X=24×Mm​Mg​​
where X is the carat rating, M_g is the mass of pure gold, and M_m is the total mass of the alloy.

• 24 carat = 99.9% purity (fine gold)
• 18 carat = 75% purity
• 12 carat = 50% purity

Historically in England, the carat was subdivided into grains and quarts, providing a finer measurement of gold purity. Today, the millesimal fineness system (expressing parts per thousand of pure metal) is increasingly used in trade and hallmarking. Common fineness levels include:

Alloys and Types of Gold

Gold is frequently alloyed with other metals to improve strength and alter colour.

• White Gold: An alloy of gold and at least one white metal such as nickel or palladium. Nickel-based white gold is strong and ideal for rings, while palladium-based alloys are softer and more suitable for gemstone settings.
• Rose Gold (or Russian Gold): A blend of gold and copper, giving a reddish or pink hue. It gained popularity in Russia in the early nineteenth century.
• Green Gold: Formed by alloying gold and silver, omitting copper. The result is a pale greenish-yellow colour often used in enamel work.
• Chip Gold: A modern form of bullion in which small gold ingots are vacuum-sealed in credit-card-shaped packaging, ensuring purity and authenticity. These are available in weights ranging from 1g to 1 ounce and typically have .9999 fineness (99.99% pure gold).

Historical Context

Gold has been revered since ancient times. The first gold coins were issued by Egyptian Pharaohs around 2700 BCE, primarily as gifts. Later, King Croesus of Lydia (560–546 BCE) standardised gold coinage for general circulation, marking a milestone in economic history. In China, the Ying Yuan coins appeared during the 6th–5th century BCE, further demonstrating the global spread of gold as a medium of value.
For centuries, gold was the foundation of monetary systems. Under the gold standard, currencies were linked to a fixed quantity of gold, ensuring monetary stability. However, after the United States abandoned the gold standard in 1933, gold ceased to be used in everyday commerce. Today, global economies operate under fiat currency systems, though gold continues to serve as a store of value and hedge against inflation.

Industrial and Technological Uses

Gold’s electrical conductivity and resistance to corrosion make it valuable in electronics, telecommunications, and aerospace engineering. It is used in high-energy applications, precision connectors, and reflective coatings on satellites and spacecraft. Though silver is a better conductor, gold’s chemical stability ensures durability in harsh environments.
Additionally, gold finds use in dentistry, medicine, and catalysis, owing to its non-reactive nature and biocompatibility.

Gold Mining and Production in India

India has been renowned for its gold since ancient times, with extensive evidence of early mining activity. Modern gold mining in India began in 1870, though production has remained modest compared to global standards. The main producers are Bharat Gold Mines Ltd. and Hutti Gold Mines Co. Ltd., which together produced about 2.5 tonnes of gold in 1995, compared to the world’s total output of 2,272 tonnes.
The Kolar Gold Fields (KGF) in Karnataka, once one of the world’s deepest mines, operated for over a century before closing in 2003 due to declining reserves and rising costs. Presently, Deccan Gold Mines Limited (DGML) is the first private sector exploration company in India, conducting projects across Karnataka, Andhra Pradesh, Kerala, and Rajasthan.
Despite India’s long history of gold mining, the country remains the largest importer and consumer of gold globally. Demand has far outpaced domestic production, with imports valued in billions of dollars annually. To address this, the Indian government has encouraged joint ventures between domestic miners and foreign companies to enhance exploration and production.

The Gold Exploration Process in India

The search for gold in India follows a structured, seven-step process:

1. Literature Survey: Review of geological data from agencies such as the Geological Survey of India.
2. Geological Mapping: Identification of favourable geological formations using field surveys and satellite imagery.
3. Identification of Gold-Bearing Zones: Sampling rocks, soils, and sediments to locate anomalies.
4. Three-Dimensional Sampling: Conducted through reverse circulation (RC) and diamond core drilling to determine ore characteristics.
5. Estimation of Global Resource: Assessment of total gold content based on sampling results.
6. Pre-feasibility Exploration: Close-spaced drilling to confirm resource reliability and mineability.
7. Feasibility Exploration: Final sampling through surface and underground methods to estimate economically recoverable reserves.

Global Gold Production and Investment

According to the World Gold Council, annual global mine production is around 2,500 tonnes, with about 2,000 tonnes used for jewellery and industrial purposes, and 500 tonnes absorbed by investors and exchange-traded funds. Despite steady output, demand often exceeds supply, prompting central banks and financial institutions to play a major role in balancing the market.
As of recent decades, central banks have held nearly one-fifth of all above-ground gold as official reserves. The Washington Agreement on Gold (1999) limits member nations’ annual gold sales to under 400 tonnes, stabilising global prices.
Gold remains a preferred investment due to its stability and historical reliability. It is one of the few assets that maintains value across time, unaffected by inflation or currency devaluation.

Gold Fingerprinting and Modern Science

Advanced scientific techniques such as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) allow precise identification of gold based on trace elements. This “gold fingerprinting” process can link samples to their original mines, helping trace stolen or illegally traded gold. Even gold that has been refined or “salted” can often be traced to its source.