how to determine gold weight in quartz specifi gravity test

Introduction

Gold in quartz specimens has always fascinated people due to their beauty and potential value. Determining the weight of gold within quartz is essential for any collector or investor. A commonly used method to determine the gold weight in quartz is the specific gravity test. This test relies on the principle that different minerals have different densities, allowing us to calculate their weight in relation to water. This article will guide you through the specific gravity test to accurately determine the gold weight in quartz specimens.

The Principle of Specific Gravity

The specific gravity of a substance is defined as the ratio of its density to the density of water at a specific temperature. For example, if the specific gravity of a material is 2.5, it means the material is 2.5 times denser than water. Specific gravity is a crucial property used in mineralogy to help identify and classify minerals.

Understanding the Specific Gravity Test

The specific gravity test relies on the fact that gold is much denser than most other minerals commonly found in quartz specimens. By comparing the specific gravity of a quartz sample to that of known density references, we can determine the weight of gold in the specimen.

The specific gravity of pure gold is approximately 19.3, while common minerals found within quartz, such as quartz itself (2.6 - 2.8) and pyrite (5.0), have significantly lower specific gravities. This stark contrast enables us to identify and quantify gold within quartz.

Preparing for the Specific Gravity Test

Before conducting the specific gravity test, there are a few initial steps and preparations you need to undertake:

1. Choose a Suitable Sample: Select a quartz specimen with visible gold within it. Ensure that the sample is representative of the entire specimen, avoiding sections that contain impurities or other minerals that might affect the test accuracy.

2. Clean the Sample: Thoroughly clean the sample to remove any dirt, debris, or oil. This ensures accurate measurements during the test.

3. Obtain Density Standards: Acquire density standards to compare with the quartz specimen. Common density references used in the specific gravity test for gold include pure gold, pyrite, and quartz.

Performing the Specific Gravity Test

Now that you have prepared the sample and obtained density standards, it's time to perform the specific gravity test. Follow the steps outlined below:

1. Weigh the Dry Sample: First, weigh the clean and dry quartz specimen using a high-precision scale. Record its weight in grams (g).

2. Weigh the Suspended Sample: Attach a fine nylon thread to the specimen using adhesive tape. Submerge the quartz specimen in a container of water while suspending it from the thread. Ensure the specimen is fully submerged but not touching the sides or bottom of the container. Use a precision scale to measure the weight of the suspended specimen and record it.

3. Calculate the Volume: Subtract the weight of the suspended sample from the weight of the dry sample to find the weight of water displaced by the specimen. Water has a density of 1 gram per milliliter (g/mL), so the difference in weight between the dry and suspended specimens corresponds to the volume displaced in milliliters (mL).

4. Obtain Density Values: Using the density standards you acquired, measure the weight of each standard using the same procedure as above. Use these measurements to calculate the densities of the standards in grams per milliliter (g/mL).

5. Calculate the Specific Gravity: Divide the density of the dry quartz specimen by the density of a reference mineral, such as quartz or pyrite. The result is the specific gravity of the quartz specimen.

Interpreting the Specific Gravity Results

After calculating the specific gravity of the quartz specimen, you can interpret the results to determine the weight of gold within the quartz. Here's what the specific gravity value indicates:

1. Specific Gravity Less than 1: If the specific gravity of the quartz specimen is less than 1, it suggests that the sample is not pure quartz or that the calculation might contain errors. Check your measuring techniques and ensure the accuracy of your density standards.

2. Specific Gravity Close to 2.6 - 2.8: A specific gravity value within this range indicates that the quartz sample does not contain substantial amounts of gold. It is likely just pure quartz or possibly contains small traces of other minerals.

3. Specific Gravity Higher than 2.8: When the specific gravity surpasses 2.8 and approaches the density of pyrite, there is a strong possibility of gold being present within the quartz specimen.

4. Specific Gravity Close to or Higher than 5: If the specific gravity of the specimen is comparable to or exceeds 5, it is a clear indication that gold is present in significant amounts within the quartz.

Summary

Determining the gold weight in quartz specimens is a crucial step for any collector or investor in gold. The specific gravity test is a reliable method to assess the quantity of gold within a quartz sample. By comparing the specific gravity of the quartz specimen with known density references, such as pure gold, pyrite, or quartz, you can accurately estimate the gold content. Remember to choose a representative sample, clean it thoroughly, and follow the specific gravity test procedure meticulously. The specific gravity test provides valuable insights into the composition of your quartz specimen, helping you determine its true value. So go ahead and conduct this test to uncover the hidden treasures within your gold-bearing quartz specimens.