|
Post by vegasjames on Jun 8, 2022 12:16:26 GMT -5
Posted this on some other rock boards since so often people just post a pic and ask what it is without any information to hep with ID such as hardness, density, general location found, streak color, acid reactivity, etc. Any info you can supply can help with ID. Also clear, photos general and close up, dry and in natural lighting.
Anyway, to show how hard it can be to ID stones from just a pic I posted this first pic asking for guesses. Most guesses were obsidian, which in incorrect. Then I posted the second pic pointing out that it is the same stone. Both are dacite. Black dacite from Southern Nevada and green dacite from Northern Nevada.
|
|
|
Post by vegasjames on Jun 9, 2022 11:50:21 GMT -5
Video on dacite
|
|
|
Post by Peruano on Jun 9, 2022 17:27:20 GMT -5
Good point. I often have to just move on when heavy opinions are offered on the basis of cursory sterotypes and there is not enough info to confirm or refute assumptions. Thats the whole basis of stereotypes, they always work because they are seldom tested and reject anything that does not fit the dubious criteria.
|
|
|
Post by vegasjames on Jun 9, 2022 17:54:49 GMT -5
Good point. I often have to just move on when heavy opinions are offered on the basis of cursory sterotypes and there is not enough info to confirm or refute assumptions. Thats the whole basis of stereotypes, they always work because they are seldom tested and reject anything that does not fit the dubious criteria. My biggest pet peeve is when people call any copper bearing rock "chrysocolla". I have even seen people call malachite "chrysocolla".
Chrysocolla is copper silicate and is very soft. So it is a specific mineral.
Adding to the confusion of some people teaching beginners the bad habit of calling all copper minerals "chrysocolla" is the name silcated chrysocolla, also known as gem silica. Silicated chrysocolla is not chrysocolla at all, but is rather chalcedony stained by copper salts.
I have even had people call stones that I know 100% are not chrysocolla, confirmed by many tests, chrysocolla. It is just such a prevalent thing in the rock hounding groups to call all copper minerals and copper ores "chrysocolla".
|
|