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Using a 10X Hand Lens

A standard tool used by geologists is a 10 power (10X) hand lens. One preferred type is a 10X Hastings Triplet made by Bausch & Lomb. The term "triplet" indicates that the instrument has three lenses, layered to make a stack.

A right handed user brings the lens up to the right eye with the right hand. Then uses the left hand to bring the object to be examined up to within one inch of the lens. The left hand is moved slightly to bring the object into focus, while holding the lens in a fixed position. The left eye is kept open while using the lens to examine an object.

It would have been difficult to show you the specimen to be examined. My left hand was holding a digital camera.

Two of the three objects shown are to be examined. They are fragments of reddish brown sandstone. The sandstone is called the Iron Hill member of the Windrow formation. Remnants of original deposits can be found on top of bluffs or lands at relatively high elevations in southeast Minnesota.

Iron Hill rock specimens are found near our home. Neighbors collect them for landscaping purposes.

I used a digital microscope with USB connection to my desktop computer to simulate using a 10X hand lens.

The sand grains are seen much more clearly at 60X.
They are clear particles of silica. They are rounded by weathering on a beach. Back and forth movement of shallow water caused the grains to rub against one another. The reddish color comes from an iron bearing coating. Perhaps it is an oxide of iron, such as hematite. Do you see how geology is an interpretive natural science? I have told a short story based on training, experience, reading, and guesswork.

I used a sharp-tipped steel tool to scrape particles out of a rock specimen. Do you own a drafting set? Obtain a small divider from the set.

Use a photo program to enlarge image grains01.jpg. Print the enlargement. Use the divider to measure grain sizes. For an elongate grain, measure and average length and width. Obtain 25 measurements with sizes in random sequence and without bias. Keep a list of the 25 sizes.

The power is 60X. Notice one grain is rounded and practically has a diameter equal to 1 mm.

Hopefully your interest in geology is keen. You can obtain a hand lens at Kooters.

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