Help with Maryland Rock IDs

[kriss]

I'm super new to rock identifications so a little direction and help would be appreciated! I found this rock in Maryland along a stream. I haven't done an official hardness test, but it appears very soft. Speaking of which, does anyone have a good rock kit recommendation? Or what should be included in a kit? Thank you!

 

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[kriss]

The red rock attached was found in the same location as the black one. I'm thinking the red one is a form of sandstone?

 

[fuss]

Hi Kriss, try taking the pics again in daylight outside, I have a feeling that the camera got the colors wrong inside with the lamp lights. The second one looks like a granite rather than sandstone, the first one is tough, possibly amphibolite (metamorphic rock)

 

[kriss]

Hi Kriss, try taking the pics again in daylight outside, I have a feeling that the camera got the colors wrong inside with the lamp lights. The second one looks like a granite rather than sandstone, the first one is tough, possibly amphibolite (metamorphic rock)

Okay, I'll do that. And thank you!

Further info on the black rock (and pardon my lack of educated descriptors): it looks like black specs that are being held together by... dirt? I'm not sure. I can rub particles off with my finger. The texture is rough.

Below is what I believe is the same type of rock but in a different style.

 

[fuss]

I have the picks listed here.

https://geology.com/store/collections/hardness-kit.shtml

 

[kriss]

Thank you! I was actually just looking at those.

 

[Red-Coat]

Some important things to know:

Hardness testing (whether using a proprietary kit or everyday items) is for minerals. It’s virtually useless for identifying rocks composed of multiple minerals or matrix-supported material. The exception is when you have a rock in which only one mineral is present or is sufficiently dominant that it determines the overall hardness.

If a rock has protruding crystals of minerals then you can of course test those by orienting the specimen to make that be the contact surface. It can sometimes help point towards the identity of what rock type you have, but in most cases tells you very little. The situation is very different if you are testing individual minerals, since that’s what the Mohs hardness scale is really designed for.

The same applies to streak testing, but a ceramic tile with an unglazed back is nevertheless a very useful item. You won’t get far in identifying rocks without a good quality magnifying loupe, ideally with multiple lenses for different levels of magnification. Both an ordinary magnet and a powerful ‘rare-earth’ magnet are essentials. A small UV flashlight is also a useful thing to have.

A club-hammer with a selection of chisels would be a good accompaniment and no self-respecting geologist would be seen dead without an “Estwing” geological hammer. The ownership of an Estwing automatically raises the esteem with which one is held in the rockhound world, with consequent privileges as illustrated below.

 

[kriss]

Some important things to know:

Hardness testing (whether using a proprietary kit or everyday items) is for minerals. It’s virtually useless for identifying rocks composed of multiple minerals or matrix-supported material. The exception is when you have a rock in which only one mineral is present or is sufficiently dominant that it determines the overall hardness.

If a rock has protruding crystals of minerals then you can of course test those by orienting the specimen to make that be the contact surface. It can sometimes help point towards the identity of what rock type you have, but in most cases tells you very little. The situation is very different if you are testing individual minerals, since that’s what the Mohs hardness scale is really designed for.

The same applies to streak testing, but a ceramic tile with an unglazed back is nevertheless a very useful item. You won’t get far in identifying rocks without a good quality magnifying loupe, ideally with multiple lenses for different levels of magnification. Both an ordinary magnet and a powerful ‘rare-earth’ magnet are essentials. A small UV flashlight is also a useful thing to have.

A club-hammer with a selection of chisels would be a good accompaniment and no self-respecting geologist would be seen dead without an “Estwing” geological hammer. The ownership of an Estwing automatically raises the esteem with which one is held in the rockhound world, with consequent privileges as illustrated below.

Thank you! I will definitely look into those things!