How to ask an "Identify this rock" question
This guide is refered to rocks. If you think you have a fossil and not a rock, follow this guide
Example of a good question for a rock.
1) Describe where you found it
Be as specific as you can (just country or state is not enough!). What part of the world? Was it on a beach? Did you find it lying on top of the ground or did you have to dig for it? Were there lots of them around or was this the only one?
Note that if you got the rock as a gift or you bought it, you won't be able to provide a location, so your question will most likely be closed as "off-topic".
If you can, post a picture of the place where you found it. Let us a link to Google Maps or another online mapping service, with a pin on the exact place (single click on the place to pin, and copy the URL). Some places are covered with Google Street View and this may allow us to take a look at the place.
2) Post a well-lit, sharp photo with a scale
Take a sharp photo in bright white lighting next to a scale or ruler of some sort. Try to use daylight (but not direct sunlight) or bright white fluorescent lights. No flash. Make sure that the rock is well lit but don't saturate the image. If possible, use a plain background, such as a sheet of white paper. Also remember to either get the units of your scale in the picture or post it in the question. If the rock has a visible crystal structure, make sure that it is clearly visible in the photo.
If the piece is a rock and not valuable, break it an picture a fresh surface, as suggested here.
Note: while a good photograph is important, it is not a substitute for a written description. Images of unknown things cannot be searched. For search purposes, questions should provide an image, and also describe the image in as much relevant detail as possible.
3) Describe its properties
If you have broken your piece, describe the properties at the fresh surface.
What color is it? What kind of lustre does it have? Is it made up of layers? Can you see grains? How easy is it to break pieces off? How homogeneous is it? Does it seem unusually light or heavy for its size?
Does it leave any streak on a paper?
Name its main property (color, structure) in the title (as suggested here).
3.1) Test its hardness
Test the mineral’s hardness on the Mohs hardness
scale. This is pretty easy to do by comparing it to some common household items. The list below gives the hardness of some
common objects; if these objects can scratch
your rock, then the rock is softer, otherwise it is harder.
- Fingernail: 2.5
- Penny or other US coin: 3
- Knife blade: 5.5
- Glass: 5.5
- Steel file: 6.5
- Quartz: 7
- Diamond: 10
3.2) Measure its density
Weight it and measure its volume as shown here, so we will know its density.
4) Be prepared to answer follow up questions
More than likely some more information will be needed to identify your rock. Users will post clarification question in the comment section of your answer. If the questions only need a one line answer, then leave it as a comment. If the question requires a longer answer, then edit your post to include the additional information.
This tag will help identify your question as a identification question and make it easier to find for people that can answer your question.
6) Name your question in a relevant way.
"Help me identify this rock" or "Rock identification needed" are very unspecific, and won't help you get good answers. A title like "Rock ID: soft, white, from Dover, UK" will help your question to stand out, and will also make it more interesting to experts in the region, who might have a better idea about the geology of their area.
Why was my question closed as "off-topic"?
If your question doesn't address the points above, it makes the question vague with many possible answers and low confidence. If you haven't responded to comments and have not provided enough information, your question will likely be closed as off-topic. If this happens, please edit your question to include the things above, which will automatically nominate it be reopened.