5-Chapter 5 Diploma Weight, Density and Specific Gravity

High-density liquid is used for?

High-density liquid can be used:

To separate mixed materials and similar-looking stones by specific gravity, allowing the efficient extraction of heavier particles from lighter ones.

To pick out the odd stones from many small stones

to distinguish between two similar or small stones,

Specific Gravity (SG)

The ratio of the weight of a substance to the weight of an equal weight of water.

di-iodomethane

An organic heavy liquid with a specific gravity of 3.33, used for SG measurement.

1-bromonaphthalene

An organic heavy liquid with a specific gravity of 1.49, commonly used for lighter samples.

Archimedes’ principle

States that an object immersed in a fluid experiences an upward force equal to the weight of the fluid displaced.

Hydrostatic method

A technique to determine the specific gravity of a material, providing accurate results except for stones under 1 ct.

SG = 2.65

Result achieved by dissolving a piece of pure quartz in a mixture of di-iodomethane and 1-bromonaphthalene.

SG = 3.05

Result achieved by dissolving a piece of tourmaline in a mixture of di-iodomethane and 1-bromonaphthalene.

SG = 3.33

Result achieved using only di-iodomethane.

Differential evaporation

A factor that can influence specific gravity measurements.

Spring balance

A device used for measuring the weight of larger stones during specific gravity measurements.

Single-pan balance

A specific measuring device used for weighing smaller stones during specific gravity measurements.

Which 2 organic SG liquids or heavy liquids are used for SG measurement?

1. di-iodomethane (SG 3.33)

2. 1-bromonaphthalene (SG 1.49) - commonly used for lighter samples as it provides a different density measurement that complements di-iodomethane.

Explain the proces, the stones used to get the SGs with heavy liquids

1. SG = 2.65;

   1. Start with di-iodomethane, add 1-bromonaphthalene, and add a piece of pure quartz until it freely dissolves/suspended in it.

2. SG = 3.05;

   1. Same as above, but with a piece of tourmaline. Add a piece of tourmaline until it freely dissolves/suspended in it.

3. SG = 3.33

   1. only di-iodomethane

If the displaced liquid weighs more than the stone. What happens?

The stone rises and floats.

This means the SG is less than that of the high-density liquid

If the displaced liquid weighs less than the stone. What happens?

The stone sinks to the bottom.

This means the SG is greater than that of the high-density liquid

name two hydrostatic methods for finding the SG

The spring balance

(stones larger than 2 ct and rough)

The single pan method

(also for smaller stones)