Sonnet help!!

Hey there. I'm a grade 10 IB student, and i'm in the midst of an English project. Our project is to analyze a sonnet of our choice. The sonnet I chose is an imperfect sonnet, and i'm unsure of it's form. Could anyone help me? I'm pretty sure it's an imperfect Petrarchan sonnet, but again, I need help.

This is the sonnet...


A Conversion by F.C. Kolbe


Behold that dark brown chrysalis, seeming dead--
Can such things live? Will life's reviving might
Arouse this sleeper from so dark a night?
Yes, see!--there issues from it[s] tomb-like bed
A creature from whose airy wings are shed
Bright beams of living, many-coloured light.
Thus have I seen a spirit take its flight.
Over its wings had error's meshes spread
The bonds of lie and prejudice and hell:
And the beholder in an underbreath
Sighed sadly as he whispered, "This is death!"
But no--a power thrills through the lifeless shell;
And into glorious morn the spirit springs,
The light of heaven gleaming from its wings.

[Tdol]

The first eight lines fir the ABBA ABBA rhyme of a Petrarchan octet, but the last two lines follow the English sonnet pattern more. It seem to me that this is a bit of a hybrid sonnet.