The Sheridan Silver streak air rifle was made from 1949 up to the 1990's after that it became the Blue Streak.
It was made in 1975
From Pyramyd Air (See the link Below)
Your rifle was made in 1977. It's one of two models, here is how to determine which one is yours. Measure your rifle barrel Model CB Blue streak barrel is 19.5 inches. Model CB9 Blue streak barrel is 19.38 inches 36.75 overall. It also has a Monte Carlo stock ( cheek rest).
Made in 1974
There are 3 versions of the Sheridan Blue Streak. See the link below for the 2nd version. BTW today Crosman owns the Sheridan and Benjamin line of air guns. This link is from Crosman
The color of the cobalt streak is blue
There are several variations of this rifle. The CB Blue Streak and the CB9 Blue Streak along with CW and CBW with Williams Peep sight. Crosman owns Sheardon and Benjamin. During the 1990's they put both name on the rifle. Later they separated the names again. Unfortunately you did not state the condition of the rifle so no estimate of value can be given. Is it Excellent, Very good, Good, Fair or Poor? Re-post you question with the model name and condition so I can give you an estimate.
The Blue Streak has been in production from 1995 to present. If you want more Information I suggest you contact Crosman who owns both Benjamin and Sheridan. See the link below.
It all depends on age, use, and condition of the rifle. Is it in Poor, Fair, Good, Very good or Excellent condition. Sheridan made 4 different model C series. The C Silver Streak, C9 Silver Streak, CB9 Blue Streak, and C9BP. Which one are you asking about?
The streak color of azurite is light blue to blue.
Around $100 in good condition.