Diamonds are the only gems that are made up of a single element- carbon. Natural diamonds take millions of years to form.
The diamonds that we get today were formed millions of years ago about 120-200 km below the earth’s surface.
The rocks in the earth’s upper mantle contain carbon. Due to variations in temperature, this carbon gets pushed deeper down where it melts under high temperature and pressure. When the temperature reduces, the carbon again gets solidified into a new rock.
Under perfect temperature and pressure conditions (a rare phenomenon), the carbon atoms in the molten rock get crystallised to form diamonds. If the temperature rises or the pressure drops, then the diamond crystals may melt partially or completely. Thousands of years after diamonds are formed, they are transported to the surface by volcanic eruptions.
Diamonds may also be formed due to the high pressure and temperature at the site of meteorite impacts.
How and Why do flowers develop their scent?
Flowers produce scent to attract pollinators or to keep harmful insects or animals away.
When a plant grows, it produces certain essential oils that decompose to form volatile oils. These oils are usually present in petals but they can also be found in fruits, leaves, barks and seeds. When the oil evaporates, the flower gives off smell. The type of fragrance depends on the chemical composition of the volatile oils.
No two flower species have the same scent although their colour and petal structure may look quite similar.
The purpose of the scent is to lure pollinators. Plant species pollinated by bees and flies have sweet scents, while those pollinated by beetles have musty or fruity odours. Large flowers such as Rafflesia arnoldii and Titan arum smell like decomposing corpses and the smell attracts their pollinators, the flies.
Flowers give off scent only when their prospective pollinators are most active. Thus plants like the jasmine that are pollinated by moths and bats bloom at night and emit a sweet fragrance.
While some plants emit strong scents to keep animals away, the Venus flytrap uses its scent to attract insects which are then ‘eaten’ by the plant!
Picture Credit: Google