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Measuring the specific gravity?
  
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AngelL




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PostPosted: Dec 29, 2021 21:28    Post subject: Measuring the specific gravity?  

Hello everyone. My name is Angel and I live in the greater Seattle area. I am a fifty-six-year-old disabled man who has three wonderful children in my life. Our relationship would be challenging to define so I’ll pass on trying; suffice to say they are my world and I’m fortunate that they feel the same. The two girls caught the rock bug about a year ago. Apparently, the bug was contagious and I was infected Monday morning when I woke up to all their rocks on the breakfast table. This is a powerful strain.
I spent most of Monday and Tuesday trying to sort through what they have and identify what I could. I didn’t make much headway. They found a box of rocks at a yard sale for free over the Summer and it turned out that most of them were tumbled rocks. Going through pictures on the internet, stopping only to order a couple of books on the topic, I found that tumbled stones are even harder (for me) to identify than rough samples. Undaunted, the girls and I have spent the entire day measuring the specific gravity of a hundred or so rocks. Today wasn’t about identifying so much as collecting information so that we can apply it tomorrow. Come to think of it, if anyone knows of a more comprehensive chart of rocks and minerals specific gravities, we’d sure appreciate it. As of now, we’ve spliced three such charts together and there’s still a lot of gaps.
Glad to be here and I look forward to getting to know you all and seeing how deep this rabbit hole is.
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James Catmur
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PostPosted: Dec 30, 2021 05:22    Post subject: Re: Measuring the specific gravity?  

Angel, welcome

This page may help you with specific gravity.

https://www.mindat.org/advanced_search.php

As you will see we do not deal with tumbled rocks and do ask that you do tests (specific gravity, and hardness are a good start)

https://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487

James

AngelL wrote:
Hello everyone. My name is Angel and I live in the greater Seattle area. I am a fifty-six-year-old disabled man who has three wonderful children in my life. Our relationship would be challenging to define so I’ll pass on trying; suffice to say they are my world and I’m fortunate that they feel the same. The two girls caught the rock bug about a year ago. Apparently, the bug was contagious and I was infected Monday morning when I woke up to all their rocks on the breakfast table. This is a powerful strain.
I spent most of Monday and Tuesday trying to sort through what they have and identify what I could. I didn’t make much headway. They found a box of rocks at a yard sale for free over the Summer and it turned out that most of them were tumbled rocks. Going through pictures on the internet, stopping only to order a couple of books on the topic, I found that tumbled stones are even harder (for me) to identify than rough samples. Undaunted, the girls and I have spent the entire day measuring the specific gravity of a hundred or so rocks. Today wasn’t about identifying so much as collecting information so that we can apply it tomorrow. Come to think of it, if anyone knows of a more comprehensive chart of rocks and minerals specific gravities, we’d sure appreciate it. As of now, we’ve spliced three such charts together and there’s still a lot of gaps.
Glad to be here and I look forward to getting to know you all and seeing how deep this rabbit hole is.
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Firmo Espinar




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PostPosted: Dec 30, 2021 07:27    Post subject: Re: Measuring the specific gravity?  

Hi Angel.

Welcome to FMF.


You can begin reading various fantastic threads about rocks in the link:


FMF Guide of Rocks :


Regards.
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AngelL




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PostPosted: Dec 30, 2021 08:51    Post subject: Re: Measuring the specific gravity?  

Thank you both for the warm welcome.

James Catmur wrote:
Angel, welcome

This page may help you with specific gravity.

https://www.mindat.org/advanced_search.php


I appreciate that very much.

James Catmur wrote:


As you will see we do not deal with tumbled rocks and do ask that you do tests (specific gravity, and hardness are a good start)

https://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487


You may want to be sitting down for this. :) I already knew. I did something rather strange before posting. I read the rules and familiarized myself with the forums focus. Don't recall the details but a thread that pops to mind immediately was the 'This is a mineral forum rather than a rock forum' and 'newcomers typically are interested in three things...' Oh shoot, my memories getting unreliable -let's see... garage or yard sale, pass me down from grandma or grandpa and (what is probably a rock) from a stream or something during a camping trip'.

I'm starting with the polished rocks to get them out of the way as none of us are particularly interested in those but it would be disappointing if we did (as unlikely as it may seem) have something special we over looked as a result. Plus, I figured it might be good practice before we get into our natural specimens. Frankly, watching the girls get excited about learning how to measure specific gravity and then give me another job because 'they've got this' was worth the price of admission. If every sample turns out to be colored glass - it was still an awesome experience.

Again, I appreciate the welcome and direction.

Angel
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James Catmur
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PostPosted: Dec 30, 2021 11:25    Post subject: Re: Measuring the specific gravity?  

Angel

That is great - we often get people who have not read our 'rules' and it takes time to convince them that we really cannot help as it is not our area of expertise (or interest)

James
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Jordi Fabre
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PostPosted: Dec 30, 2021 13:11    Post subject: Re: Measuring the specific gravity?  

DIY Specific Gravity Kit (tutorial) - (19)
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Peter Megaw
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PostPosted: Dec 30, 2021 14:26    Post subject: Re: Measuring the specific gravity?  

John Betts gave a great talk on a really simplified SG test at Rochester a few years back, He generated a video of it which is posted on John Betts Fine Minerals website.

Add the www. to the below or simply Google: John Betts Rochester specific gravity... and you'll find it. Easy for a lay person to understand and apply

johnbetts-fineminerals.com/jhbnyc/articles/specific_gravity.htm

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AngelL




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PostPosted: Dec 30, 2021 16:00    Post subject: Re: Measuring the specific gravity?  

Peter Megaw wrote:


Add the www. to the below or simply Google: John Betts Rochester specific gravity... and you'll find it. Easy for a lay person to understand and apply


Please don't receive this comment as an indication of a lack of gratitude; for I am. Moving forward however, it might be helpful to know that although I am new to all things geological, I do have a background in the sciences (B.S. physics/mathematics) So, while I'm confident that my ignorance shall be on display often during my tenure here, I'm enough of a nerd that just for fun, I've compared the specific gravity of household items that no one should ever know the specific gravity of. :)

What I can't figure though, is how you offered the link, but when I tried to quote it I got the following message:

Quote:
Your message has been rejected by our automatic antispam filter.
The text that caused it to be rejected was:

johnbetts-fineminerals.!com/jhbnyc/articles/specific_gravity.htm
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Pete Richards
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PostPosted: Dec 30, 2021 16:54    Post subject: Re: Measuring the specific gravity?  

Remove the exclamation point!

And welcome!

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Collecting and studying crystals with interesting habits, twinning, and epitaxy
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Jordi Fabre
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PostPosted: Dec 30, 2021 17:28    Post subject: Re: Measuring the specific gravity?  

Links within the message forum
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SteveB




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PostPosted: Dec 30, 2021 18:42    Post subject: Re: Measuring the specific gravity?  

Welcome and its great to hear you and your girls have caught the bug, Most of us start with pretty tumbled stones to get us hooked on being interested in rocks, leading on to local places to explore and maybe finding more interesting mineral or fossil specimens depending on the local geology we have practical access. While trying to identify your tumbled assortment gives you good practice on some methods it closes off many of the tools of identification , doing streak tests, luster and cleavage etc become destructive and sometimes even point less with tumbled stones. But as tumbled stones are typically of poor quality to being with it makes the job harder as confusion as to what the stone is in the first place, you are not going to have something rare and expensive thats been tumbled, they are typically the scraps from someone elses pickings already. Even the blandest rocks become more visually interesting by a polished tumble. There are so many Quartz based rocks and minerals out there, a ton of quartz varieties, to start with, quartzites, jaspers chalcedonies, agates, etc, trying to differentiate from a tumbled variety is next to impossible, they all have pretty much the same hardness and specific gravity. I’d suggest getting out in nature and exploring stony areas and hills where exposure of its “interior” are more prevelant (eg roadside cuttings are common where layers are visible to explore and inspect up close. While books on rocks and minerals are full of very pretty specimens these are the cream of the crop and something you’ll likely never see with your own eyes, let alone find for yourself out in nature, but its not impossible. Getting out in nature and learning about geology will help you “read the landscape”, just get out there and look around and see what you can find for yourself. You’d be amazed at the number of rural roadsides that yield agates and petrified wood and quartz crystals just laying around on the surface. Suburban environments you can expect the top few feet of the ground has been bulldozed and maybe refilled with soils to grow lawns especially for a wide area around and buildings with helped with construction. So digging in your yard is not likely to represent the true geology, unless you live on a rural property where the area is mostly for animal grazing . Exploring creeks and rivers is good as they cut through or erode the natural geology there exposing whats inside the ground. It really just takes a little time and interest to pay attention to the ground to explore and find awesome mineral specimens for your collection/display. I still cherish some early memories I have of finding crystals and agates and have them still decades on even though they aren’t that spectacular, they are just marvelous creations of nature and its a fun activity to spend with your children just to get outdoors and explore, anywhere, any time, take notes of where you explore and gather whatever specimens take your interest, then have fun trying to identify them at home, beaches are also great to explore as the erosion into cliffs etc reveal much to explore and learn from. Just be mindful of posted rules in national parks etc, and dont just jump fences into properties to explore, ask first. Don’t expect it to be a profitable hobby, it can be entirely free to learn and participate in but it can be very expensive too if you get carried away. I highly recommend to look up on youtube Nick Zetner as he’s a long time geology teacher and is a charismatic instructor, you and you girls can learn much from his videos even though they are mostly based on his local region, the same geological concepts apply globally and can help you understand your local region too. Look for fossicking groups in your area, lapidary clubs often have outings to local areas to find specimens to cut and polish. There is so many avenues to explore and even the ones you aren’t specifically interested in can have much to teach and inspire you, you can’t know until you get outside and look.

As for the specific gravity scale tables you asked about, its clear everyone has their own it seems that varies subtly, both naming can differ as can ranges of values as many are compiled from sources with certain intents. I put together a spreadsheet long ago from such tables and generally I find its only a guide to get me to ballpark possibilities for a specimen, plus keep in mind specific gravity of rocks is pretty meaningless, as rocks are made of assorted minerals and SG/hardness values are for a pure mineral (eg crystals), If you use a “highly” accurate digital scale in your SG testing be mindful your breathe on the scale can alter your results a lot, the smaaler the specimen the harder it is to weight too accurately and it important to not spill water to effect you results. Distilled water should give you much better result than tap water that contains dissolved mineral salts etc). For hardness I highly recommend a set of Hardness Scribes instead of a nail and piece of glass as those simple tools are only for very generalised measurements and if you choose a nail made from harder or softer metal you cant really make a good measurement value. A scribe set will cover from values of 1 to 9 with a consistant measuring set, as making a determination is also about your touch and best done at home with instruments, but the basic general kit with knife blades etc is meant for in the field and no big deal if you lose the kit and typically you take a testing item specific for finding a certain hardness specimen you want to find in the field, its not for data collection or positive identification. You also want a good loupe/magnifying glass you can use in the field to examine crystal up close (learning crystal habits is important to identification as well. There are plenty of good cheap ones around, a 10x is all you need, built in lights only help sometimes but more a gimmick. As you learn and get interested you should put together some gear for use at home to explore and measure specimens with care and accuracy, a cheap digital microscope is a great way to examine samples up close, spot minute crystals growing inside holes and crevices in a rock etc. Common to mining and prospecting are cloth specimen bags ( often muslin with a draw string and maybe a black label sewn in to label where the specimens in the bag came from. They are cheap to buy and it would be good to put together a “kit bag” using one for each of you, containing a magnifying glass, field notebook with pencil to take notes and a few empty sample bags. One of the same kit for each of you so no arguments in the field, make whatever notes you want really about where you go and what you find and the sample bags are ready for you to collect items of interest in the field. Think of it as a “ready to go bag” just grab and go out exploring. Each of you is likely to develop your own interests so will take different notes and maybe expand the Go Bag with some other essential items to help your area of interest. Maybe all of you will get bored of the hobby but I hope not, What I learnt as a child fossicking I have built on over the years and as I moved around in life I was able to explore my local geology within my limits of skill and knowledge at the time, but always finding something interesting to add to my collection and memories and avenues of interest to research at my own pace and my knowledge just grew but was universally applicable wherever I lived or visited, Certainly more fulfilling than having my face in a phone screen all the time. And years later I would re-examine specimens I found long ago and found new things about them to explore and research. With Covid having forced many to school from home you may be able to contact local mining operations and organise a time to take your girls out to see how mining works in action and get to explore and examine specimens you wouldn’t be able to reach normally. Like it or hate it but mining is here to stay and often brings to light many spectacular specimens, while the NewAge lot is mostly manufactured and altered specimens, Agates do not naturally form in DayGlo colours and taking a large chunk of worthless quartz and cutting it into the shape of a crystal doesn’t make it a crystal. Its a segment that doesn’t really offer anything much of value to knowledge of rocks and minerals, it more about selling pretty trinkets, but they aren’t as nature formed they and I’ve never seen evidence any “spiritual” etc claims have any validty. So just beware if you’re interests start to expand to buying specimens from ebay, they are often not what they claim to be.

Sorry for the rambling but I wish you and your girls all the best and that you find your explorations to be rewarding for the fun of it and your researches will give you long lasting skills of observation and measuring that apply in many fields of life or work. Its your journey in the hobby, so you set your rules and goals, there are many pitfalls to avoid when you start buying specimens (look for rock shows or similar that come up in your area to go visit and buy specimens, meet great people and learn) but just getting outside and finding interesting rocks is a great place to start, no money or equipment needed plus of course exploring local hills and valleys you have a lot of chances to photograph the beauty of nature, learn about plants and critters too, plus the fresh air and exercise is good for everyone.
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AngelL




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PostPosted: Dec 30, 2021 19:30    Post subject: Re: Measuring the specific gravity?  

SteveB wrote:
Welcome and its great to hear you and your girls have caught the bug, Most of us start with pretty tumbled stones to get us hooked on being interested in rocks...


Amazingly, neither one of the girls are much interested in the tumbled stones with a rare couple of exceptions. It was my littlest, back when I was still carrying her, who would call out for me to stop and pick up a stone that caught her eye. About 75% of the time, it didn't look nearly as interesting to her up close. The problem was (and still kind of is) that she anthropomorphizes everything. If we put the rock down after picking it up, it'll hurt it's feelings, don't you know? I don't take her to pet stores. Anyway, she started this whole thing, sucked her big sister into it and then me.

SteveB wrote:
Don’t expect it to be a profitable hobby...


It's already become profitable! We are having fun and spending time together. I know you meant financially profitable; but I'm at a point in my life where I measure wealth and profitable a bit differently than most..

SteveB wrote:
I highly recommend to look up on youtube Nick Zetner...


That is our next stop tonight; thank you!

SteveB wrote:
Look for fossicking groups in your area, lapidary clubs often have outings...


We've reached out to a local club which happens to be the most active one in the state meeting three times a week for classes and workshops along with regular outings. $20/yr with a family rate - $28/yr for the three of us.

SteveB wrote:
Sorry for the rambling but I wish you and your girls all the best....


Are you kidding me? This was awesome! Great information, direction, and frankly, kindness for taking the time. Thank you. :)
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AngelL




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PostPosted: Dec 31, 2021 08:29    Post subject: Re: Measuring the specific gravity?  

SteveB wrote:
I highly recommend to look up on youtube Nick Zetner as he’s a long time geology teacher and is a charismatic instructor, you and you girls can learn much from his videos even though they are mostly based on his local region, the same geological concepts apply globally and can help you understand your local region too..


I had to return to this thread to share that apparently Nick lives right down the street. As such, his local area IS ours. Unbelievable good fortune!
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SteveB




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PostPosted: Jan 01, 2022 04:35    Post subject: Re: Measuring the specific gravity?  

Glad I could help. I had a query from someone, and I wanted to clarify something I suggested for you. I mentioned a digital microscope; there are a ton of them around and are mostly garbage, I use an Andonstar, which has a stand, a zoom camera and a screen with a card slot to save images. I think this style is perfect for your needs. You and your girls can view your finds up close together on the screen and you can all point to features and ask questions easier together as you learn, traditional microscopes are not really appropriate or easy to use for this purpose as my Andonstar is. There are small handheld and pocket digital microscopes with high magnification claims which are meaningless and due to the tiny area of focus just impractical to use. You only need 10x magnification anyway in practice for most uses and a simple geologists loupe is all you need in the field and at home. But for the kids I think it really helps you explore together at home and with being able to capture photos too is great for illustrating school projects, be it rocks, insects, leaves, flowers etc, just an awesome tool I wish I had growing up, I had to try to sketch things I saw in my simple regular microscope my dad gave me and of course school projects I typed up, pre home computer and internet days. Feel so old now.
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