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Nick_Huntington




Joined: 17 Sep 2019
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Location: California

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PostPosted: Apr 10, 2020 20:11    Post subject: Any help would be appreciated  

Hello, I found these last year while doing some work in a vineyard near Lake Sonoma. The reddish areas have a waxy luster and a streak that is reddish brown (was hard to get it to leave a streak).

I chipped off a piece from a larger rock I couldn't get loose and had to leave there. The chipped off piece has a lot of different things going on with it. That photo is of the freshly exposed side. The other side of it is similar to the look of the other samples.

The different pieces I found have slightly different heft to them and I have gotten specific gravity calculations from 3.4 to 4.1.

There are some old manganese prospects in the area and several outcroppings of chert with black manganese oxides on the property so I was guessing this is one of the manganese silicates for the areas with red/pink/yellow color but unsure of what the small grey/black crystals are. Any thoughts about what minerals are making up these rocks would be welcome.

Thanks,

Nick Huntington



Sample 1.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: 2cm by 3cm
 Description:
 Viewed:  8237 Time(s)

Sample 1.jpg



Sample 2.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: 4cm
 Description:
 Viewed:  8236 Time(s)

Sample 2.jpg



Samples with ruler.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: Ruler is in inches
 Description:
 Viewed:  8233 Time(s)

Samples with ruler.jpg



Streak.jpg
 Description:
Streak of the reddish waxy area
 Viewed:  8231 Time(s)

Streak.jpg



Chipped off sample.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: 25cm x 8cm
 Description:
 Viewed:  8238 Time(s)

Chipped off sample.jpg



Closeup of chipped off sample.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: 4cm by 3cm
 Description:
Close up of area on left side of chipped off sample
 Viewed:  8234 Time(s)

Closeup of chipped off sample.jpg



Large sample.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: 24cm by 12cm
 Description:
A larger piece
 Viewed:  8233 Time(s)

Large sample.jpg



Large sample closeup.jpg
 Mineral: Manganese silicates and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: about 4cm by 3cm
 Description:
 Viewed:  8233 Time(s)

Large sample closeup.jpg



Close up 1.jpg
 Mineral: Manganese silicates? and ?
 Locality:
Sonoma Lake area, Sonoma County, California, USA
 Dimensions: about 3cm x 2cm
 Description:
close up photo of the chipped off piece
 Viewed:  8233 Time(s)

Close up 1.jpg


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Jordi Fabre
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PostPosted: Apr 29, 2020 14:03    Post subject: Re: Any help would be appreciated  

Massive minerals and rocks are not easy to determine Nick. We can say a lot of guesses but just by a photo and without distinctive details I'm afraid that you need go to some Show or mineral club close your area and ask there if some one is familiar with what you have.
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Bob Harman




Joined: 06 Nov 2015
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PostPosted: Apr 29, 2020 14:36    Post subject: Re: Any help would be appreciated  

Agree with Jordi. Also, being rocks and not a mineral, specific gravity and streak have little meaning as they are meant primarily for minerals.
Bob
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Bob Carnein




Joined: 22 Aug 2013
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Location: Florissant, CO


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PostPosted: Apr 29, 2020 18:16    Post subject: Re: Any help would be appreciated  

You need to try the streak of the black mineral. My guess is that it will turn out to be hematite, which has a red-brown streak.
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