Is My Rock Calcite?

So, you’ve found a shiny, crystally rock - good for you!

It kind of looks like Quartz, but you want to figure out if it’s just Calcite.

There are two quick methods to help you out:

1.  the UV Light Test

2.  the “Fizz” Test

Gather your supplies and set up a place to work free from clutter [you don’t want to spill the vinegar 😊].

• Your Unknown Mineral
• A Quartz Sample (if you have one)
• Vinegar (any household vinegar will do)
• Disposable Gloves (this isn’t completely necessary, but it keeps your hands clean)
• Disposable Container (I got the cute little dish at DollarTree)
• Pipette (link: https://www.amazon.com/dp/B07MSNQYTV/ref=emc_b_5_t)
• UV Light (link: https://www.amazon.com/Black-Light-Flashlight-JAXMAN-enhanced/dp/B06XW7S1CS)

[ Note: The JAXMAN is no longer available, but the link above should get you started on your search for a similar one ]

Find a dark room where you can use your UV light. If you have a sample of Quartz, shine the UV light on it to get a feel for what Quartz looks like, mostly blue from the UV. Then shine the UV light on your Unknown Mineral. In most cases, calcite crystals will glow orange, yellow, white, or green.

My Results

• Quartz under UV - no fluorescence (just the blue glow from the light)
• Unknown Mineral - some fluorescence (orange tint), possible Calcite present

Pour a small amount of vinegar into the disposable cup.

Extract a small amount using the pipette.

Drip a few drops onto the Quartz and check for any bubbles.

My Results

• Nothing happened. Nothing should happen. Quartz does not react to vinegar.

Find an inconspicuous place on your Unknown Mineral to drip the vinegar. Before you apply the vinegar, be prepared to watch closely because if there is a reaction, it will be small and brief. Add a few drops onto the specimen. Quickly look very closely at the spot where you dripped the vinegar. Look for any signs of bubbling.

My Results

• Quite a few bubbles appeared and then dissipated. See Step 5 for a Video of the bubbles! (Look closely at the center of the rock)

Don’t forget to clean your mineral after the “Fizz” Test. Rinse it under running water for 15-30 seconds.

My shiny, crystally Unknown Mineral looks a lot like Quartz, but is really Calcite!